I have a temperature gun which I use obsessively and a probed thermometer that I don't really trust, so I'm getting a new better one. Here's my question, apologies if it's stupid. I followed the "how to set up a 20 gallon long with pictures" guide and I admit, and I'm sorry, that I didn't use the aluminum foil part, but I trust my hygrometer well enough and humidity is on point. (I mist the tank, have a waterfall and obviously fill the water dish daily).
The question is... why the one thermometer, and why is the probe centered over the UTH? Wouldn't that only measure the hot side? Again, my therm is wildly inaccurate compared to my very nice heat gun so I guess I can't even tell for sure. Should there be two thermometers, one probe on the warm side and one one the cooler side? I for some reason can't wrap my head around one thermometer for two different temperatures. Again I apologize very much if this is a stupid question. Again, I'm getting a better thermometer delivered in two days but I wonder if I actually need two.

He of course has a thermostat for his UTH.