Eh. If there is a caster in my group, then I will use it.
If I see a caster(obviously a caster- ie, in caster glamour or visible astral magic balls things) in the alliance, I will use it.
If the whm in my group decides to go Cleric>Holy spam, then I will use it.

And, when I do use it, it will most likely be used during the dps check of the fight (ie, Titan's heart/superbombs, ramuh's minions, trash pulls in towers ect)

Other wise, think I'll save it for when whm needs ballad.

Or if a melee ACTUALLY asks for Army's.....because SE still hasnt given me a tp bar...:I