While I've been looking at a lot of RPG systems over the past year I've noticed something. A lot of people will focus on differences in combat systems or skill systems or realism in a particular game vs. another game. Something that I don't see a ton of discussion about though is healing, and that's odd because it really impacts the flow and pacing of a game. It's not flashy and it may not even show until the game is actually played for a few sessions - maybe that's why it's overlooked - but I wanted to look at some examples and talk about different approaches.
Basic D&D - Hit Points return at 1d3 per day. A 1st level character will have 11 or fewer while a 3rd level character might have 30. If clerical healing is unavailable that means it takes days of game time to recover full health. Also, this doesn't scale well as the level rises. Expert adds no new healing rules so a 9th level fighter could be out for 1-3 months of game time. Magical healing is essential beyond the first few levels to avoid extended downtime. Even then a Cleric can burn a full day's worth of spells just healing up one character.
AD&D - Each day of rest restores 1 hit point. After 30 days this goes up to 5 hp per day. So the 9th level fighter with 100 hit points would take a month of rest to get to 30 hp's, then it "only" takes 14 more days to fully recover. This
is why some campaigns went on for years and years of game time - healing! Scaling here is terrible. Magical healing is required here too and can pretty much heal one up overnight if the Cleric does nothing else - or unless multiple characters need help.
AD&D 2E - 1 hp per day of rest, 3 hp per day of complete bed rest. Again, a 9th level fighter takes 3 months of bed rest to recover. Not really different from 1E.
D&D 3E - Hit points return at 1 per level per night of rest. This does at least scale but at low levels is actually slower than Basic D&D from 20 years before. A 10th level fighter could easily have 100 hit points - it's going to take him 10 days of rest to get back to full health. Scaling down to a 1st level fighter with 10 hit points, it would take him...10 days of rest. Well, at least it's consistent, although being consistently bad isn't really a bragging point. Now there is the "long term care" option under the Heal skill, and that can get the healing up to as high as 4 hp's per level per day - that's much better, but it does require another character making daily skill checks but at least it does not require magic. That means the same 10th level fighter could be up and about after 3 days, a major improvement. Mechanically there has been no real change to natural healing times in 20+ years os D&D at this point. Magical healing is still essential to not taking a month off in the middle of an adventure to recover although the Heal skill does take the edge off of it. Even with that though 3 days of uninterrupted rest in a dungeon is not going to happen, necessitating a retreat for full recovery.
Savage Worlds - PC's have 3 wounds and there are ways to mitigate damage during an encounter inherent to each character. Assuming all of that failed and a character fell back on natural healing with 0 wounds remaining then they make 1 Vigor roll every 5 days and unless they are very weak they will heal back 1 wound, possibly 2. Call it a max of 15 days for most PC's to go from 0 to full health. Like a lot of more recent game designs, unless a character is killed in the middle of combat, recovery is very quick and pretty easy in Savage Worlds. There may be magic or superpowers available too, making it even easier.
Mutants and Masterminds - As might be expected in a superhero game damage in M&M is pretty easy to get over. The worst condition that can be imposed on a character (assuming they aren't dead) is "Disabled" and that has a chance to be healed once per day at a 50% or more rate of success. Remember that's *natural* healing - no powers or hero points or anything else. There are all kinds of external healing options in a supers game plus goodies like "regeneration" - downtime is rarely a problem in a supers game using any rules system.
Star Wars (d6) - The worst case scenario is a mortally wounded character who has been stabilized - he will need 35 days to make the first healing roll and then will need about another 3 weeks to get through the rest of the healing rolls to be fully recovered. That's pretty hefty downtime but there are bacta tanks widely available and that cuts the same character's healing time down to 1d6 days - period. That's why bacta tanks get installed on the smuggler's YT-1300 before it ever lifts off. Some of us tend to think of d6 Star Wars as a more modern game design but it came out when AD&D 1E was still in print. I suspect healing would be different now if it was a brand new game. Evan as-is though, bacta pretty much handles the healing potion/handy Cleric role. Don't leave home without it!
Star Wars Saga Edition - Base natural healing is 1 hit point per day per level. Considering that the weakest first level characters start with 18 hit points, and some can start with over 30, this is horrible - going to 0 hp's means you are out for a month! This heal rate is ported over directly from 3E D&D but the hit points are much greater. Fortunately there is a heal skill here too (Treat Injury) and it has multiple ways to increase this rate using various skill checks, typically doubling or tripling it. A 10th level Jedi might have 100 hit points and this would cut his downtime down to 5 days or less. There are also Bacta Tanks in this system too and they can add another multiple to Treat Injury checks, cutting the recovery time down to 2 or 3 days with a decent skill level. There are also some options for healing through the Force, which could be faster or easier if there is no healer handy. At first glance I was appalled at Saga's healing times and I may still house rule something, but with skill and with equipment or a force-user it gets pretty reasonable.
Hero System (5E) - Body is similar to hit points and the average man has 10 Body. He will recover 4 of those per month, and medical care can double that. Most Hero characters will have 10-20 body, and will recover anywhere from 5-8 points per month. Call it 1-2 months for complete recovery. That's pretty long, but like Savage Worlds Hero tends to get used for Pulp type games, Fantasy games, and Supers, so there is a lot of healing available in most campaigns, speeding that time up considerably. I've never had healing time pop up as an issue in any of my Hero games over the years.
Shadowrun (3E but applies to earlier editions as well) - The worst wound status a character can take is "Deadly" the base time for healing up from that is 30 days Success here takes the damage level to "Serious" which takes a base of 20 days, then moderate which is a base of 10 days. Now there are modifiers here for whether the character is in a hospital or a gutter and for being extra tough but there are penalties too for being a mage or for having a bunch of cyberware and multiple successes can cut the time down by a lot but assuming he makes 1 success each time he is given the chance, then a character could be out for 2 months! Even a serious wound can take a PC out of the game for an entire month of game time. This is tremendously inconvenient given that SR's typical playstyle involves covert ops with a time limit. If you are stealing a code today for a mission tomorrow night and your street samurai gets harmed, he's probably out for that next mission. Bring on the backup character!. Now there is magical healing available but it has to be done during or right after combat and healing a cybered-up character gets very tricky and they tend to be the ones that need it the most! It's a rough system and screwed up more than one of my campaigns when too many of the runners got wounded in too short a time to allow them to finish a mission. If I ever run it again there will be some serious adjusting of these rules.
So looking at most of these systems if a character gets hammered and put down hard, it's going to be a month or more to recover if they're using natural healing. This is likely to destroy any time pressure in an adventure the DM is running and may stretch believability even when there is no overt time pressure - such as, say, clearing out a dungeon in D&D. In one-off games this might not be a big deal ("sorry you're out" or "bring in another character" both being perfectly viable options) but in an ongoing campaign it causes all kinds of wonkiness as the party takes a month off of game time while someone recovers in the hospital, or they go on without him meaning the player gets left out and the party is weaker by that much. Neither option is great for getting things done so one system went a different route.
D&D (4E) - characters recover full hit points after an 8-hour rest. Period. In between, they have varying numbers of "healing surges" of 25% of total hit points which represent combat healing and can be added or subtracted through various types of magic, creature attacks, powers, and items. Now it is still possible to die in combat or from falling off of a cliff or other hazards of the adventuring life and a character will usually spend time moving around at less than full hit points but the one thing they will NOT do is spend weeks or months of campaign time sitting on the sidelines, and that greatly changes how a campaign runs. It removes a lot of the micro-managing of healing and downtime and cure light wounds spells and all the other trivial hassles of dealing with wounded characters and lets the game focus on getting things done.
I was weirded out by it at first - it was a little too abstract for me. Having used it for 20+ sessions of 4E now though, I have to admit I'm a convert. No more wasted camping days while the cleric goes "all heal" and fixes up the fighters. No more months off at high levels recuperating in the keep because the cleric got eaten in the last expedition. Even ignoring the healing surges thing a game like Basic D&D can benefit from the "Extended Rest" rule - all hit points return overnight if you get 8 hours of sleep. They were already pretty abstract even then - they're certainly not a measure of purely physical damage after about 1st or 2nd level - so why not carry that concept the rest of the way?
It's very liberating - there's still the threat of being blasted by a dragon or engulfed by Gray Ooze - the danger is still there - but the hassle factor is nearly non-existent. Games with "point" mechanics - Fate points, Force points, Hero points, etc. - probably don't need it as they usually have instant recovery mechanics already, but for games that do not - Shadowrun, older versions of D&D - they can really benefit from this if it's how you want your game to go.
Which brings me to my other point - a lot of this depends on whether you want a more realistic game or a more cinematic game. Realistically, it takes time to fix a damaged human body. Cinematically, it doesn't. As I've gotten older I've gotten a lot less interested in realism in my games. Runequest's self-impaling combat mechanics just annoy me now. Twilight 2000's long healing times are certainly realistic but they also make the game less fun when all you can do is limp around at half speed and try not to get shot. I have gone way over to the side of "- the Movie" as in whatever game I'm running it's "That Game - The Movie" where everything is bigger and badder and we don't have time to play through multiple random encounters for every hex of movement on the big scale map nor do we have time to spend a month healing up because watching other people play while you do nothing isn't fun - it's a waste of very limited game time. If you die in combat, hey, that's the breaks - roll up another character. But if the penalty for serious injury is actually worse than that, then there's a problem - a fixable problem in my opinion.
I realize not everyone agrees with my preference for the cinematic approach and that's OK - I'd probably still play in your game if I had the time and the opportunity. This is just my take on one particular area of RPG's and it works for me now. 20 years ago I felt differently and I expect in 20 years I may feel differently as well. For now though, it's what I like.