Here's a normal answer from a normal person: Finished the game (as in beat the final boss, with one friend in coop) after ~60 hours. At that point I feel 100% done with the game and bored as ♥♥♥♥ with the grind (which both of us were already at the ~40 hour mark).

That gametime also includes one restart because we nearly dropped the game at the 20 hour mark since we didn't look anything up on wikis and thought we soft-locked ourselves (died on mountains, didn't find a single crypt in the swamps). We restarted after reading the wikis because our seed felt tainted.