I wouldn't. If they are a different wattage to each other and all plugged into a power strip for example, the power strip will receive power through the thermostat at 1 wattage. Let's say the thermostat has decided to supply 9 watts to your power strip. On a 4"×12" strip of flewatt on shelf 1, that might be full power and dangerously hot. The second shelf may have 11"×12" flexwatt and those 9 watts supplied by the same power strip might only heat it slightly. Let's say the third shelf has your thermostat probe and a 17watt uth. The input of temperature from that pad is how your thermostat gets the information to send out 9 watts of power and has no way of knowing how that is impacting anything else on the power strip that does not have a probe attached to it. I hope this helps and I've only ever used this method when I had matching (identical wattage) uths.