What if you have choices about how you get down to the level where the final boss fight is?
Say, after level 3, you have a choice about level 4-5 (den of thieves) and level 4-7 (goblintown). On level 5 (den of thieves) you have a choice between level 6-7(goblintown) and level 6-9(temple of evil). On level 7 (goblintown) you have to make a choice between level 8-12 (Stinking swamp) and level 8-12 (Tombs of the Reaver) on level 9(temple of evil) your only real choice is levels 10-12 (Tombs of the Reaver). All levels 12 lead to a common level 13, "The Big Room", where you have more choices to make. And so on.
Each of these branches has monster and item generation that's strongly thematic, "tilted" toward monsters and treasures and items of particular types. Your path downward is meant to be influenced by what you think you can handle with your particular combination of abilities and what kinds of treasures and skills you intend to train. You can miss a particular thing that you don't think you can handle, but it may mean backtracking. Likewise if you feel like you have to get both of two alternatives, you can backtrack through the second of them (and maybe come down a third).
Now, here's my question. Assuming that you don't get experience for killing anything too far below your level, so there's no experience reward for doing a lot of backtracking, and a score bonus for completing the final boss fight faster so you'll actually get a higher score if you don't, and you have the ability to buff selected equipment when you level, so usually sticking with stuff you found earlier will give you stronger kit anyway...
Do you still feel an OCD urge to go back and forth and back and forth until you've seen every last square inch of the dungeon that can be seen, and had in your hands to make choices among every last bit of equipment that's generated among all the branches? Do you still feel that you MUST do so in order to "truly win?" Do you feel that you are being "railroaded" into inefficient play because you HAVE TO do this dance to see all of the content in every game?
In other words, does this sort of thing frustrate the "completionist" urge so much as to ruin a lot of players' experience of the game?