A couple of small tests of unfinished content has made me realize that people will happily exhaustively explore a space for no other reason than trying to make sure they see everything.

It's obvious in retrospect maybe but when player character is hammer they'll ensure no stone is left unturned in their search for nails.

I worry a lot about if there's enough narrative motivation for a player to keep crawling but there being uncrawled tiles is all the motivation they need.