I've been battling for the last hour or so, and a few hours before was another hour or two of battling, but I still haven't cleared the Nightfall Bandit Dungeon, when do you finally clear it?

Eventually you'll reach the final boss, once you defeat them you'll clear the dungeon. I'm not sure how long it'll take you since I don't know how quickly you battle with your current party, but just keep at it and you should get there.

Each dungeon, after a certain number of fights, will have a certain event- in NBD, after a handful of battles you'll get a "there's a room with x amount of y's" (or something to that effect- the exact things vary), and after a handful more you get the first door puzzle, and completing it will let you fight the first miniboss.
Repeat- a handful of fights, a room with"# of b", handful of fights, puzzle, miniboss if success
repeat again, get number, third puzzle, input the three numbers if you want the third miniboss.
Handful more fights and you run into the Boss (no minibosses are needed to get to this, they're all optional)

If you've been going for hours, either you're not doing battles (winning battles required to progress because that's just how regions 1 and 2 are programmed), or you're not in a dungeon (Nightfall Bandit Camp has a similar name but is not a dungeon), or something has gone wrong, because I'm pretty sure it's only like... 10 battles between each puzzle door? * checks* yeah, something about 10 (total of about 40 non-(mini)boss battles in NBD.)

Alright, will do, I made sure I was in the dungeon, the one with the red text and the skull, and I have been. I'll just fight another 100 battles until I get my second miniboss :')
Thank you <3

Update: I Finished :D

About 7k gold earned, Thanks for the advice!