Grimrock

Myself, I rather prefer that when I clear an area ~it stays clear; unless it's specifically part of an unsolved puzzle that monsters reappear.

I'm not a big fan of infinite respawns either. They have their place in some spots for sure, but definitely not a constant theme.
I would be interested in a puzzle where you have to stop the respawning of monsters though.

Well that i say in another reply its not in all places infinite respaw, just some area to train, new spells combinations, increase skils since DM dont have level just skills increase.. like Sword, Bow, Magic, and keep game challenge.