Not as a healer, but doing leveling roulette and get aurum vale with a whm.
Never uses cooldowns, never uses regen, never eats the molboro fruit, wipe twice on the first boss.

Putting aside everything else he isn't doing, I just say he should be using regen.
I'm ignored.

Later when this happens at the coincounter as well I really stress that he should be using regen cause it's one of their best as well as most efficient healing spells.
"but regen uses a ton of mp"
*facepalm*