There was one instance where I ran a dungeon for the first time as a healer, and went into a cutscene before the boss. Even by the time I decided to cut it early for whatever reason the tank decided to jump in early and they were stuck without a healer and died horribly. Despite me skipping the cutscene 10 seconds after when I felt it'd be long and sprinted towards the boss arena, it got closed off before I could make it.

Needless to say, they were embarrassed.