Hmmm depends on situation and type of mobs. Depending on the player and how they manage their TP it's normally not worth it and faster to focus on one. Then use Aoe Tenka Goken for better dmg without sacrificing TP. Sometimes it can be a bit difficult to understand unless you experiment it your self.

If you look at the TP usage on some if your support characters don't replenish your TP you become a bit useless for some time. So best way to explain it is to just play it your self, AOE, and see what I mean. Once you reach 70 and depending on the dungeon or what your doing it will make more sense.