What the issue is as the pad builds up heat it lets out gas.The gas builds up and when it gets to a point it cant escape from under the pad so it will push the pad back of the disk the evacuate.
This is why it gets worse as it gets hotter, more heat more gas.
Slot your rotors, when on slot is leaving the pad surface another slot must be entering, basically you always have a slot under the pad.
The amount of slots in a disk is in relation to pad size,small pad more slots.
Jim