Ditto. It also helps if you camp without a water source, and in cold weather you don't get as cold when you stop for the night.
In really hot weather, I try to stop at a shelter or other shaded place with water during the day and would take a five hour break or so. That way I can do most of my mile in the morning or just before and after dusk avoiding the worst of the heat and sun.
In rainy, hypothermia-inducing weather I make it a point to take several short breaks throughout the day, generally at least one an hour. I might not think I need it, but I do, and if I try to stop for 15 minutes or more I can get too cold, if I don't stop enough I get cold and tired. So many short breaks work best then and I try to eat my main meal whenever it's warm and dry enough to do so.