Since this thread isn't long enough I thought I would throw my two cents in.
When, in a game, would you want to keep players injured for more than a day?
I can certainly recall lots of games that involved holing up to heal, resting a night, healing again, then resting again to bring the Cleric's spells back on line (back in 2E).
In 3E we just had stockpiles wands of cure light wounds for that.
I can certainly imagine fun storylines involving injured or tired people. But it seems to me that the hitpoint mechanic is a bad way to do it.
1. Characters of equal level but fewer hitpoints (mages, rogues) heal up faster than fighters, which strains my suspension of disbelief.
2. Hitpoints in every RAW system ae generic. 100 applications of a 1 hit point cure is ultimately the same as one 100hit point heal spell (except in tedium). So as soon as you permit magic items that head and such, you get rid of that problem (unless you take them away).
3. When spells are the main way to restore hitpoints the party will be unbalanced, since spell casters will be blowing spells (and resources) to elevate the the other players to fighting ability. So the cleric is down to few spells while the fighters are ready to go.
I think a better technique would be, for those wanting more grit, would be some kind of mechanic specifically for wounds. For people who want wounds to make you less effective, there could be a system for that, for those who want to simulate the 'wearing down/time to recover aspect there could be a system for that.
i am a fan of optional wounds/fatigue as a player option. So for example, a PC can either go to negative hitpoints, or at her option sustain some lasting injury. Then a player can decide, is it worth being hampered with a broken limb, or partial blindness, to stay in the fight for a few more rounds, or should I go down, and hope my buddies can either defeat the baddies or get me healing. Alternatively give bonus healing surges that fatigue, exhaust or knockout a person (after the encounter).