True but I've heard of times where they stay are certain heat levels for a long time which is why people sometimes assume they don't need one. Or they think unplugging it after a time will keep it from getting too hot. Heat pads are notorious for malfunctioning though and they are not supposed to go past a certain max temp (at least that's what some packages say). I hear about malfunctioning UTH all the time. When they do they get overheated fast.