This is a great concept, which makes me actually want to play 5E! I feel like the disconnect between the character optimization side of the game and the narrative realism side of the game always bugged me, and this is a really interesting take on it. I might even write my own speedrun dungeon.

My headcanon for this format: This dungeon is a highly realized dream simulation sustained by a team of oneiromancers who sleep in shifts (each oneiromancer can simulate floors equal to their level) at a famous adventuring academy sponsored by a wizard cabal. Clearing the dungeon solo is a necessary requirement for graduating with honors.

Woah! Got that done quick.