Advice from experienced quick fixers

long story short I got a 3 test to take

first time I took hand warmer off in parking lot and it stayed fine in my groin

second time left it on and it stayed so hot the lady asked was I ok since I took so long getting it to cool down

my question is do I trust the first process again and use my body heat or did I just get lucky ? how likely is it that if I take the warmer off In the parking lot at 98F, that itll stay above 90F long enough?

thanks in advance