If you're gonna heat it, put a layer of bead foam or (better) foil-faced foam covered with masonite or something. Even the heat produced by chickens will be more effective with insulation.
Yeah, I know, we're insulating AND ventilating, but it makes a more comfortable coop.
I mostly ran heat over the winter to improve
my sleep: to keep rocketMom from waking me up in the middle of the night wondering if the hens were okay. I turned it off when she squawked about the power bill.
{edit to add}
What you don't want to do is shock animals with massive rapid temp changes. Wild birds acclimate day-by-day to the weather, and they've had thousands or millions of generations to get used to it. Chickens are hardy, breed dependent, but they can get used to warmth and then can't handle cold. It has to do with feathering, behaviors, and housing design. Wild birds don't stand around in cold wind like "mad dogs and Englishmen" out in the noon day sun, either. They'll find a way to hunker down when things get really bad.
Also, wild birds aren't cranking out an egg every day. That takes a toll on the chickens. Take care of them and they'll take care of you.