Well, the model that HoML uses is simply "when you become exhausted, you refresh." This is, after all, what people effectively WANT. The text couches it as a 'long rest' (probably should abolish that terminology) but it has no connection with any specific narrative. The normal procedure is that the players decide they want a refresh, and they accept whatever the consequence for doing that is, which just means that the GM frames a new scene. He could choose to frame it 5 minutes after the last scene, or 5 years, but the PCs are guaranteed to be at full strength. They could pay a terrible price of course, but its up to the players to decide what they want to do.
What terrible price do you speak of, can you give me an example?
Obvisoulsy I'm not AbdulAlhazred, but my take on the notion of "terrible price" would be influenced by 13th Age and Burning Wheel.
13th Age rules for fleeing and for refreshing (pp 166, 171, 187):
At any point, on any PC’s turn, any player can propose that the fight is going so badly that the characters have to flee. If all of the other players agree, the heroes beat a hasty and successful retreat, carrying any fallen heroes away with them. In exchange for this extraordinarily generous retreating rule, the party suffers a campaign loss. At the GM’s discretion, something that the party was trying to do fails in a way that going back and finishing off those enemies later won’t fix. . . .
If the party is short of a heal-up but is too beat up to press on, they can retreat, tails between their legs. Provided they can find some sort of safe place, they can get the heal-up that they haven’t earned in battle. But taking the heal-up entails a campaign loss. At the GM’s discretion, the party fails to achieve one of their goals, and they fail in some way that simply defeating the bad guys the next time around with your healed-up party won’t fix. Don’t worry; occasional setbacks make for a more engaging campaign. . . .
Normally, the party gets to take a full heal-up after about four battles. The point of the four-battle heal-up rule is to make players want to press on instead of holing up, which is what the traditional rules reward you for.
So what happens when the party has been weakened so badly that it would be madness and suicide to press on? If the party
decides to heal-up ahead of time, assuming they are able to rest, they suffer a “campaign loss” (per page 166 in Chapter 5). What does that mean? At your discretion, the situation in the campaign gets noticeably worse for the party. Ideally, the campaign loss can be traced to the decision to take the heal-up. . . . The campaign-loss rule is key to making combat meaningful. We all know most GMs probably won’t kill the PCs permanently, but if the PCs can’t fight their way through four battles, the game world suffers.
Burning Wheel Adventure Burner (pp 186, 242, 244):
It's important to keep the action moving, to keep the players interest and engaged. . . .
You do not want to rest up the characters before every dramatic situation. The whole point of being wounded or sufferng similar penalties is that these modifications make the next action more danagerous, more challenging. If the players are allowed to gather their strength before every encounter, then the penalties lose their value . . .
You must push the plaeyrs and threaten their characters. You must harry them, work them. But once they have accomplished that great goal in their Beliefs, you must back off. Once the situation has been resolved or substantially changed, you must give the reins to the players. You must frame the action so they can rest and consider their actions.
Even so, unless you're ending a campaign, you must constrain their choices. GIve them a set amount of time or resources to use. . . . At the end of the rest period, something happens. An event transpires that challenges their Beliefs in an unexpected way. . . .
The adventure-rest-practice-reequip-adventure cycle is the natural pace of the game. However, it'sthe GM's job to keep up the pressure for as long as he can without breaking the players. Don't give them a moment of peace. Throw challenges at them. When they stop for rest, move your pieces in the Big Picture. Make them say, "Uh oh. . ." Force the players to create their piece by accomplishing their goals or by spending themselves utterly. When they're wounded, broke and ragged, let them go to ground but let them know that their enemies will not rest. . . .
The practice rules are meant to allow for the passage of long stretches of time in your game. Let five years pass! . . . Let the players practicea and beef up their abilities. And let the setting and situation evolve and change meanwhile!
In 13th Age it's mechanised and is about player choices to risk PC death or concede campaign losses; in BW it's GM control over the pacing of events, with the injunction to maintain pressure on the PCs (and thereby their players) and to use moments of rest/recovery/practices as opportunities to develop the situation so as to generate new challenges. Either way, the players recognise that resting isn't "free" - it's connected to the GM's entitlement to escalate the fiction in adverse ways.
For me, at least, this is an aspect of the "story now" way of achieving the "living, breathing world".