I've only ever used it on Tanks, tbh. Aldo first, and if they need topped off throw Physick at them if there are still enemies around and the shield is still up.

It *is* your strongest raw heal spell, so if the tank is flagging and you're waiting for Aetherflow cooldown to finish and have no aetherdams left (and you don't want to use Dissipation because the tank isn't in that much trouble) and you're synced so you can't use Fey Union, it's a good thing to use. Or you're using fey Union on one tank and the other needs healing and you're low on MP.

It's not a waste of space. I absolutely recommend keeping it on your hotbar.