You've mentioned this a couple of times and each time, I have felt it an unsatisfying solution. Why have this period of time when the game allows you to heal up (unbelievably as it were) overnight? Do the players or DM just decide that "hey, my healing surges don't work because I have a bad injury". I mean, how do you even determine if you have a bad injury?
The game rules say that all healing surges are restored after an extended rest. The game rules are silent on whether this means that all wounds are healed, or the PC is able to ignore those wounds, or . . . (In the same way, the game rules are silent on what damage taken corresponds to what sort of injury on a PC, except that "bloodied" means bloodied.)
My suggestion is that if all the players at the table are agreed in disliking the notion that all physical injury is restored with an extended rest, they can simply agree that a verisimilitudinous amount of time passes between episodes in the game. When an extended rest is taken within the context of a given episode, then it can be narrated no differently from a short rest - the PCs bind wounds, take the weight of their injuries for a few hours, then resolutely return to the fray.
A wonderful mechanic, but one that's flavour grates with my sense of verisimilitude. YMOV.
Well, I'm just offering a suggestion that permits verisimilitude to be preserved without changing the mechanics. The verisimilitude still involves a potentially gonzo element, of much gritting of the teeth and pressing on regardless, but I think no more than has always been inherent in D&D. The gonzo aspects to one side, it is entirely within the power of a gaming table to regain verisimilitude, simply by (i) agreeing to the suggested break between episodes, and (ii) narrating extended rests within episodes as mental/moral recovery rather than physical recovery.
(Btw, exactly the same technique can be used by those who don't like the idea of PCs going from 1st to 30th level in a single game year or less.)
Of course, if the players feel that they are obliged to play their PCs as if the game mechanics are the physics of the gameworld, with hit points and healing surges mapping directly to physical injury and its recovery (eg they will not interpret the extended rest rules as anything but "all non-mortal injuries, however severe, heal overnight") then they will not like my suggestion. But for such resolutely simulationist players, 4e is probably the wrong game system. Likewise if you are playing a game in which the notion of "episodes" makes no sense (eg it is a sandbox game in which the entire game world is on stage all the time) then I think that 4e is probably not the right game for that sort of play.
All pemerton is saying is "if fast healing bothers you, play a different way'.
<snip>
This could come in the form of a house rule, a whole new homebrewed severe injury system, or a simple agreement between the players. In the end they amount to the same thing.
I am suggesting "play a different way." I'm also suggesting that this can be done without changing the mechanics at all. All it requires is agreement at the table to let a sufficient amount of ingame time pass between episodes.
The advantage of doing it the way I am suggesting (ie by metagame agreement with no change of the mechanics) is that there is no danger of the unfolding of events
within an episode being derailed by the need for lengthy healing periods. In my approach, lengthy healing periods only occur when everyone at the table agrees to let the time pass. When events are in motion, extended rests are simply narrated as a resolute gritting of teeth in the face of pain and injury.
I would prefer just sucking it up, thinking "oh well, the rule does not make complete sense" and move on rather than trying to house rule a ruleset that my group is still getting used to.
I hope I've made it clear that I'm not suggesting any sort of change to the mechanics. I'm just suggesting a certain metagame agreement to increase verisimilitude.