Haven't heard of the ice cube trick either. I have made masking tape 'dams' around the heal, and the goo self levels in the low/warn spots of the heal (shoe kept upside down until cured). Helps to clean the area with acetone and lightly sand and scuff the area.
McNett AquaSeal seems to be the same thing. I use it to weld drysuit neck/wrist/ankle seals to the suits. Works well on shoes.

A huge mystery to me is....how to protect the heal cups in trail runners? I wear out the heal cup fabric way faster than the soles/heals. Tried medical tape for years but even it breaks down the heal fabric. Any ideas?