As a tank, any time I've ever run into a person first doing the dungeon, I make it known I'm going to help them map the place - ie, every room's going to be explored.

If it's no one's first time on low level, it's rare I go through every place unless asked. At which point I do. Doesn't bother me. If I don't have the time for it, I don't do low level roulette.