As a healer I sometimes enjoy it when the tank grabs every mob in the dungeon and I just spam heal like crazy popping every cooldown.
But the hardest part is not knowing when the tank has pulled enough, sometimes I expect him to pull more and he gets his first heal too late and dies.

I prefer when the tank grabs like 2 monstergroups each time. It's not too easy to heal so I actually get do something (If the tank goes for one group only regen is enough to keep him up, and I don't like dpsing as a healer. I picked healer to be a healer, I don't want to hit the cute monsters )