If you could make impovements to Deep dungeon...

[Felis]

No, instead people will get frustrated and quit. You can give something longevity in other ways than by RNG. Like making it fun and not just people button mashing mobs.

The dungeon is just poorly implemented in its current form.

Low droprates, low spawnrate or RNG. Choose your poison.

Longevity is about how many times you have to do a content. It can be fun, but it don't help if everyone get every reward within the first week.
So, ask for more puzzles, but not for less time sink.