I have my thermostate inside and it just makes sure i hit an ambiant of 82 then again i use bins and i only use 8watt heat tape that doesnt get hot enough on full strangth to burn the snake. Everyone has their own methods, thermostate inside the inclosure or direct to the heat tape is a big debate everyone has there own personal preferance
8 watt heat tape unregulated gets more than hot enough to burn a snake...
Plus flexwatt doesn't really effect the air temperature inside of a cage.