Originally Posted by
Mansion
It is quite usefull, particularly on O11S as Nocturnia explained because of the heavy damage of personal AOEs / flamethrower / DoT and the positioning coming after that.
But most of the time, you can choose not to heal a raid AOE, put a Medica 2 / Asylum and it will work its way to top off the raid without using that much mana either.
And don't forget that you have a co heal that will help on this too ; sometimes WHM's potency will turn to overheal because of a shield or a parallel heal.