Perfectly normal. When the PCs stop for the night to take a break, if they have amassed enough experience points to meet the milestone, they qualify for a Long Rest (i.e. they regain spell slots, appropriate class features, etc). If they had not amassed enough experience, I simply tell them that they do not qualify at this time, the night's sleep is merely a 'lowercase rest' ( as opposed to a formal Long Rest) that all murder-hobos need to stay in tip top shape.
D&D 5E Slow Natural Healing in actual play
Perfectly normal. When the PCs stop for the night to take a break, if they have amassed enough experience points to meet the milestone, they qualify for a Long Rest (i.e. they regain spell slots, appropriate class features, etc). If they had not amassed enough experience, I simply tell them that they do not qualify at this time, the night's sleep is merely a 'lowercase rest' ( as opposed to a formal Long Rest) that all murder-hobos need to stay in tip top shape.
Saeviomagy
Adventurer
I think that if I were to want to change the game to make slower healing, I would do the following:
1. For each die of healing you receive from a source other than hit dice, you must spend a hit die, to a minimum of one die for healing that has no dice. Roll the die and add the result to the healing spell. You do not get your constitution modifier added for these dice.
2. Whenever you are healed, you may spend hit dice to get extra healing. For each Hit Die spent in this way, the player rolls the die and adds the character’s Constitution modifier to it. The character regains hit points equal to the total.
3. You may spend hit dice when someone uses a healer's kit on you, even if you would not normally get healed. For each Hit Die spent in this way, the player rolls the die and adds the character’s Constitution modifier to it. The character regains hit points equal to the total.
3. At the end of a long rest you do not heal to full. Instead you regain half your spent hit dice rounded down to a minimum of 1. After that you may spend hit dice to heal.
Long story short:
If you go adventuring for a single day, you're guaranteed to be at full health and hit dice in 5 days no matter how badly you are smashed down. You will most likely be down hit dice for a couple of days. If you keep adventuring, your hit dice will gradually spiral downwards, depending on how badly you get hurt. Since every bit of healing you do requires you to spend hit dice, you can't avoid the downward spiral if you keep getting hurt in any meaningful way.
A small healing spell can potentially give you a lot of hit points back if it's needed.
Mini heals like goodberry kind of suck. Oh well. Use them as a last resort.
Temporary hit points are great, because they don't incur the hit dice cost.
1. For each die of healing you receive from a source other than hit dice, you must spend a hit die, to a minimum of one die for healing that has no dice. Roll the die and add the result to the healing spell. You do not get your constitution modifier added for these dice.
2. Whenever you are healed, you may spend hit dice to get extra healing. For each Hit Die spent in this way, the player rolls the die and adds the character’s Constitution modifier to it. The character regains hit points equal to the total.
3. You may spend hit dice when someone uses a healer's kit on you, even if you would not normally get healed. For each Hit Die spent in this way, the player rolls the die and adds the character’s Constitution modifier to it. The character regains hit points equal to the total.
3. At the end of a long rest you do not heal to full. Instead you regain half your spent hit dice rounded down to a minimum of 1. After that you may spend hit dice to heal.
Long story short:
If you go adventuring for a single day, you're guaranteed to be at full health and hit dice in 5 days no matter how badly you are smashed down. You will most likely be down hit dice for a couple of days. If you keep adventuring, your hit dice will gradually spiral downwards, depending on how badly you get hurt. Since every bit of healing you do requires you to spend hit dice, you can't avoid the downward spiral if you keep getting hurt in any meaningful way.
A small healing spell can potentially give you a lot of hit points back if it's needed.
Mini heals like goodberry kind of suck. Oh well. Use them as a last resort.
Temporary hit points are great, because they don't incur the hit dice cost.
Li Shenron
Legend
Sorry for getting into the thread late and not reading all of it before posting... 
I agree that the "Slow Natural Healing" variant purpose is not that clear. It generally only means less HP available during the day. With the standard rules, you have a minimum of ~150% of your max HP per day (because of the rate of getting back half of your HD during a long rest). With the Slow Natural Healing variant you are guaranteed only a minimum of ~50% available (you get those HD back but not your actual lost HP). So yes, overall the game will be tougher unless you often have "empty" days with no encounters to go back to full HPs. But how that is different from having for example more monsters per encounters (or anything else than wears down your HP more) may be a matter of details.
OTOT the "Gritty Realism" variant has primarily the purpose to play adventures with very sparse combat encounters, perhaps somewhat LotR-inspired. If you have stories with sparse encounters, then this leads to either the PCs using very little of their resources or otherwise going "nova" and beat all the encounters easily (the latter however carries the danger that an occasional second encounter on the same day can spell doom to the group). In such campaigns, it makes sense to turn hours into days and days into weeks. Nothing really changes in resource management except the narrative.
If you use the "Gritty Realism" variant but do not change the rate of occurrence of the encounters, then it definitely gets very gritty, as the PCs are strongly motivated to avoid encounters as much as possible. This also makes the game more difficult for the players, so I am not sure if at the end this ends up a popular choice
When I first read the "Gritty Realism" variant, I thought that perhaps what they might have wanted is to grant to benefits of a long rest every 7 days, but with the long rest itself still taking a single night. This would have made the variant more usable because it doesn't require to actually take a break from the adventure... but from a narrative point of view would have been probably breaking suspension of disbelief.
Probably, a middle ground could be found by allowing some partial recovery of resources, but this certainly leads to a more complex set of rules.
I don't think it really works to apply the "Gritty Realism" variant rules to HP only but not on spellcasting, pretty much because of what you say here.
I agree that the "Slow Natural Healing" variant purpose is not that clear. It generally only means less HP available during the day. With the standard rules, you have a minimum of ~150% of your max HP per day (because of the rate of getting back half of your HD during a long rest). With the Slow Natural Healing variant you are guaranteed only a minimum of ~50% available (you get those HD back but not your actual lost HP). So yes, overall the game will be tougher unless you often have "empty" days with no encounters to go back to full HPs. But how that is different from having for example more monsters per encounters (or anything else than wears down your HP more) may be a matter of details.
OTOT the "Gritty Realism" variant has primarily the purpose to play adventures with very sparse combat encounters, perhaps somewhat LotR-inspired. If you have stories with sparse encounters, then this leads to either the PCs using very little of their resources or otherwise going "nova" and beat all the encounters easily (the latter however carries the danger that an occasional second encounter on the same day can spell doom to the group). In such campaigns, it makes sense to turn hours into days and days into weeks. Nothing really changes in resource management except the narrative.
If you use the "Gritty Realism" variant but do not change the rate of occurrence of the encounters, then it definitely gets very gritty, as the PCs are strongly motivated to avoid encounters as much as possible. This also makes the game more difficult for the players, so I am not sure if at the end this ends up a popular choice
When I first read the "Gritty Realism" variant, I thought that perhaps what they might have wanted is to grant to benefits of a long rest every 7 days, but with the long rest itself still taking a single night. This would have made the variant more usable because it doesn't require to actually take a break from the adventure... but from a narrative point of view would have been probably breaking suspension of disbelief.
Probably, a middle ground could be found by allowing some partial recovery of resources, but this certainly leads to a more complex set of rules.
I don't think it really works to apply the "Gritty Realism" variant rules to HP only but not on spellcasting, pretty much because of what you say here.
FrogReaver
As long as i get to be the frog
Spells and other abilities typically recharge a day at a time regardless of natural healing rates. As long as you bring one full caster healer (I'll call this a Cleric) along then worst case scenario is the party may end up resting 1 extra day so the cleric can heal them all and still have all his spell slots. All in all it won't make an actual difference because if you can rest a single night and have a full caster with healing there's rarely a reason you can't rest 2 if desired.
FrogReaver
As long as i get to be the frog
I think slow natural healing on it's own does next to nothing for the game. However, slow natural healing with any mechanic that gives a downside for players staying somewhere and trying to rest multiple days could quite interesting. I'm thinking random encounters that increase in difficulty the longer you are in one area would work nicely when coupled with slow healing variants.
Grittier is just another term for fantasy realism similarly to common sense basis vs popular impetus with modern D&D editions to displace realism with a wink and a nod game effects that favor cartoon-ish+video game+fast reward with least time and effort+monty-haul+John wick vs Godzilla+first person shooter games driven style over compelling storyline and strong role-play.
To each her own..... I suppose we could all suspend disbelief (1) by assuming all species have troll blood/regeneration genetics, or (2) yellow sun empowered supernatural mystery exponential healing rate almost as fast as the memory of fleeting disappearing scars or (3) billions of tiny microbial swarms of micro-fairies-trauma-specialists working as miraculous catalysts without fail perpetually when the 'any creature or species' only but gets a REM sleep cycle in a pitch tent munching on dried figs (but don't trip on a hidden twig and stump your kneecak when you get up to take a leak lest the invisible microswarm not unlike glimmering rains every night in a fairie dusted slumber as they spontaneously revert and evaporate along with mortal wound recovery hit points)..... for any war-ravaged flesh wounds from any damage type severity from any and all wounds up to precipice of death from life threatening injury...... Hang on .. one better.... (4) when your character of flesh and blood gets nearly disemboweled but hangs on to his spilling guts then the campsite is in your periphery after your 16 long hours of war struggle and conflict is only one more set of severe 3rd degree injury burns away from that golden moment when a marshmallow roast and a couple smores commemorate just another lingering sole hp from just forget it -it will be like it never happened if you only find a bit of spit to just rub some dirt on it and catch some zzzzs because you know what drives 5e is that tomorrow is always a brand new (entirely renewed miraculously recovered series of wound trauma) DAY - every time ..... From ICU trauma to feeling like a million platinum pieces (just like saving your legend of Zelda game progress on an old Nintendo game system). Wink and nudge and cheek thy tongue gamers! You'd think that already existing magical healing sources could stand in for this silly standard rule. Another sigh, where optional rule should have been the standard, and another fine example in the power gaming (beholders all together roll eyes)..
-wesley Munger (25 year veteran DM)
FrogReaver
As long as i get to be the frog
Or another novel idea - simply stop narrating every hit as the PC being stabbed, slashed, bludgeoned, etc. Choose your hp narrations to fit the hp recovery model you are using. If you do this there will cease to disconnects of the type referenced.
clearstream
(He, Him)
I've used Gritty Realism along with Slow Natural Healing, modified to 3-days instead of a week. That change was needed to preserve balance between short and long rest classes.
Principally, GR gave narrative space so that when the party chose to rest it always felt plausible to move the world forward. There's experientially no more laying about, as one can narrate over 3 days rest in the same amount of real time as one can narrate over 8 hours. In background, GR made the world magic economy feel a bit more reasonable. For example, the number or rezzes per year castable by a high-level cleric was dialled back considerably, which made it feel a bit more plausible that they were not always available to heroes. Etc. It favoured rogues with always available exploration abilities, seeing as spells recover less often. Overall, I would never revert to normal rests.
SNH is harder to assess. For one thing, players lean into casting all their healing spells whenever they secure a safe rest. So there is more bookkeeping around that. Hit dice themselves act as a kind of battery that characters can draw on to keep going, so what happens is there isn't too much impact on what you might call the first cycle, but once the battery is empty players start thinking about wanting to take breaks from adventuring. How that plays out is very campaign dependent. If you are interested in a dungeon-bashing campaign, or one with continuous fighting, then this will not work out very well because as others as observed it can force downtime. On the other hand, if you want to make use of downtime rules and run a more reflective campaign - perhaps one with more political intrigue - it works pretty well, because that downtime becomes a good thing.
Anyway, I tend to think of the two working in tandem. I wouldn't choose SNH without GR because I think it moves the play in a certain direction and if that direction is wanted then GR is the way to go. For instance, GR means healers aren't cycling their spells so often in in-world calendar time. Whereas normal rests possibly makes SNH kind of pointless.
Here's my take on that reasonable reply......
What does full hit points represent? Full health.
What does negative 1 hp represent? Death.
How does your model account for the slope?
It doesn't. Just because you choose to be in denial that the model represents those two extremes doesn't displace the facts.
