If you look for a rest-related theme in my games and in my posts, you will see two competing strands:
- My players, actively using rest as much as possible. Resting after spells, after fights, after travel, after calamities add extra penalties, etc. is Standard Operating Procedure for my players.
- Me, creating situations that limit rest, penalize static positioning, and otherwise push for continuous action.
Why the PCs rest is pretty obvious - combat and spells cost FP in GURPS, first aid and surgery take time, and identifying and sorting loot isn't fast. The first is the most important - the PCs freely expend FP to win fights or deal with obstacles, but then rest to be ready and fresh for the next one. I'm sure they'd argue that for every near TPK that results from resting in bad areas, there are dozens of situations they couldn't have succeeded in without rest.
Why I make rules and situations to penalize rest might take more explanation.
The reason for rules like Dogpiling, musing on Recover Strength, dungeon locales with Wandering Monsters and net-penalty rest areas (the Cold Fens dungeon levels) springs from three concurrent goals:
Force tough choices.
Punish one-solution approaches.
Make resources important.
Forcing tough choices is all about making it a real decision between "push on while tired" vs. "stay here and hope danger doesn't find us." It forces the choice between "run without the treasure" or "get surrounded by monsters and have to fight your way out.
Punish one-solution approaches is how I word the concept of making players play dynamically. You can just burrow holes through the dungeon, because the cost is high and monsters will come hurt you. You can't always lock the door and rest behind it. You can't always rest, period, because the dungeon makes rest impossible or nearly so, and thus you can't just win every fight with high-cost spells. You can't solve all obstacles with a handful of high-cost high-reward utility and combat spells.
Make resources important is probably the most self-explanatory. If you always have time to get FP back, and thus get HP back, and thus recover fully from fight winning/obstacle defeating expenditures, then FP and HP are a per-fight resource. There is no long-term cost to using them, and no risk to expending them. The campaign becomes a series of individual events with recovery time between then instead of a unified whole.
Those goals drive a lot of my decisions about how to shape the play environment. In order for it all to be a challenge, there has to be a variety of obstacles to overcome. There can't be a baseline assumption of total and safe rest, or it significantly detracts from the play style we're reaching for.
In a very real sense, a lot of PCs have died as a result of resting. Many have lived longer for it, but there are guys buried because they died in a fight that happened with a wandering monster, an ambush from monsters alerted and given 40 minutes to an hour of prep time, or from being surrounded. Equally some PCs have died because there was no time to rest (although the number is much smaller.) Making resting and recovering your temporary resources not always a sure thing means these things can happen, and it means you are making a bet. That my players seem to always take the bet that "rest and hope not to die" is better than "don't rest and rely on momentum" doesn't really change that. It does, however, mean my rulings and thoughts are skewed to "how to challenge rest?" and not "how to challenge lack of rest?"