It depends on your room, like what some of the other guys have said, just depends on what works for you. I have a ball python and leopard geckos, which obviously require different temps than a king, but I use both with them because my reptile room will drop into the low 70s at night, UTHs just give me that extra layer of.. I guess peace of mind that there's a warm spot in there that they can go if they need to. Plus if one heat sources goes out during the night I have a second running to they don't get too cold.
This mixed with good thermostats that turn off if something happens to prevent overheating, vs failing wide open, doesn't 100% eliminate any worry I have for my crew, but it makes it where if I wanted to stay gone overnight for some reason I wouldn't stress too much about how my pets are doing.