Every time somebody trots out this logic - "Would your character, who is in a deadly dangerous scenario where they are risking death at every turn, really do this moderately inconvenient thing just to improve their chances of survival?" - I am bewildered by the implied priorities. If I am truly roleplaying my character in this situation, the answer is HELL YES. That extra spell slot could mean the difference between walking out with a sack of gold and jewels, and getting eaten by a monster. It's insane not to take every scrap of advantage you can get.
This is a variation on the 5-minute workday problem. If the adventure is one where the party can stop and rest without consequences, it is absolutely reasonable and realistic for them to do so after every. Single. Fight. Real-life soldiers devote many, many, many hours to boring, repetitive activities, just to slightly tilt the odds in their favor for the few seconds they are in actual combat. What would you choose, a week of tedium ending in riches or a day of excitement and terror ending in death?
Now, if the adventure is one where there are serious consequences to stopping and resting for 2 hours, obviously one takes that into account. But if there aren't, the rational in-game decision is to rest every chance you get. As a player, I choose to rest less often than my character realistically would, due to metagame considerations (keep the game moving, get to the fun stuff). But when I make that choice, I am quite deliberately putting those metagame considerations above roleplaying.