I think I’ve figured out why this particular tactic might never have come up in the original Lake Geneva campaign. There was too much competition.
Bear in mind that the original LG campaign was a cloud, not a party. There were dozens of adventurers, all competing for gold and glory in the dungeons beneath castle Greyhawk. Now, consider this advice from the DMG:
Generally, time passes day-for-day, or turn for X number of real minutes of active play. Players who choose to remove their characters from the center of dungeon activity will find that :a lot has happened while they were away”, as adventures in the wilderness certainly use up game days with rapidity, while the shorter time scale of dungeon adventuring allows many game sessions during a month or two of game time. Of course, this might mean that the players involved in the outdoors someplace will either have to come home to “sit around” or continue adventuring in wildernesses and perhaps in some distant dungeon as well (if you are kind); otherwise, they will perforce be excluded from game sessions which are taking place during a period of game time in which they were wandering about in the countryside doing other things. This latter sanction most certainly applies to characters learning a new language, studying and training for promotion in level, or off someplace manufacturing magic items.
Given that sort of philosophy in the application of game-time, I can really see that someone venturing into the dungeons, taking 3 h.p. of damage and casting a spell, and then returning to hit the next room at full strength, would rapidly be overtaken by other adventurers who were more willing to take risks and push the limits of their resources. Otherwise, after returning to the dungeons after a couple of days’ rest and relaxation, one might well find the section of dungeon originally intended for exploration had been sacked by others.
Having that happen once or twice might well make even the most cautious of adventurer become just a tad more… adventuresome.
* One slice at a time. 😉