When applying ZAIO by hand I use the same amount of product as I would applying Z2pro or Z5pro. Take your app and make a spaghetti noodle thin line of product from bottom left to top right. Next, fold app over so you have an x of product on the pad. I can get a few panels worth with that amount and it applies very thin. With that, I'm usually ready to remove in 10-15 minutes.
Working with a pc or rotary, I can usually remove in 5-10 minutes. Does it hurt to leave it on for longer? Not in my findings. I've left it on for an hour with no ill effects.
Greg