If the New to Dungeon message pops, I'll mark if things start getting dicey in ANY dungeon, no matter my class. However, some things I think players should mark automatically; just for ease later.
Ran a Thornmarch HM for the first time, had notes from vids for it, but ALL the dps were on their own targets with no priority and we ended up wiping. one of the Healers marked things second attempt and it was like a "lightbulb moment" for the whole group.

Reason I brought that up, sometimes marking "wakes" dps to paying attention.