heatmat on all the time?

Got one of those hydrofarm heatmat, trey and dome. Should i leave it on all the time or maybe only at night when temps are in the 60s? I dont use the dome, just the trey and heatmat undert that. I also haventhe seedlings in small biodegraded containers, a little bigger then plugs.
Does the heatmat eventually just level off at a certain tempature or just keeps getting hot? Working with some 3 day old babies and worried about grtting too hot. Would onlynuse the mat for anpother week or 2 tops

They sell a thermostatic control for the heat mat. It costs more than the heat mat.

Or you could put a timer on it. ONce I have roots tho, I turn the mat off for good

Timer is the cheapest option. Heat-mat running constantly dries out the medium. Fast.

For seed starts, seedlings and clone starting, the optimum medium temp is between 75 & 80 if you can keep the space near this temp you don't need a heating pad, they don't like 90+. And using a heating pad without temp control is a "AW F...K" just waiting to happen.