What's a good humidity level for a shedding ATB?

Yesterday my 9 months old male ATB shed for the first time since i got him. During the shedding days, I kept the humidity around 75%-82% and he shed incompletly. I had to remove the rest of the skin. How high should the humidity be in order for him to shed completly?

Ideally, you want to try to aim for about 60-75% for average humidity all the time with an ATB, it can get boosted up to 80-90% during shed (when they go into blue), that isn't always needed but it isn't going to be bad either!
This is just in general and especially for a trouble shedder. I keep mine a little lower than average and only have issues with ones that are in cages with lots more screen/air flow so I do try to mist those when they are going into shed to avoid any issues.
Hope this helps.