I agree if the uth is on the glass.
You helped me out when i started using my temp gun. You told me that then and i cut my uth off cause you thought it wasnt doing anything for my tank temps. When i cut it off i found the tanks temp dropped a good bit. The way i have my setup the uth is at full power but unable to overheat the tank because of the gap.
If i had it mounted to the bottom of the tank i would make sure to have a thermostat. I really feel the way i have it now is safer. You may not agree but my numbers are constant and uth can not do any harm how it is.
Play with one just laying under a tank. You will see it heats it up pretty well without touching it. Heat rocks were the way now its uth, maybe im a pioneer of the unattached uth. Lol
If it works, it works.