When you play Illaoi and are gonna teamfight DON'T ULT WHEN YOU ARE ON like 10% HP

I seriously cannot grasp why so many people can't understand this. Whenever I get an Illaoi in my games, as we start a teamfight, she only uses her ult when she is low on health. I understand her passive heals based of missing health, but if we're going to teamfight and you ult while you are so low, not only has time been wasted where much potential damage could have been done, but the chance that you die after getting off maybe one W is so high.

I cannot list the number of times I've seen such a thing happen. Start fight, Illaoi jumps in, brawls for a bit, only as she gets low, ults, dies 2 seconds after...

Please ult when you enter the fight as many people are around you and so you can dish out as much damage as you can.

EDIT: oops i've posted this in the wrong section