They usually hide...
pert' near all the time. They will explore the cage when hungry, males will around breeding time (spring), and hatchlings seem to move about quite a bit at any hour of the day.
But adults spend the majority of their lives under SOMETHING! You find 90% of them that way in the wild, the other 10 at night on the road. Let's face it, if you are small and red, you won't live long exposing yourself during daylight hours. Corns are said to be crepuscular; active mostly during dawn and dusk. I have seen them out in broad daylight in the heat of the summer, but that is very unusual. Most I have found I was looking for by turning things over or road-crusing after dark.
Likewise, most of my adults are either in their hides or under newspaper when I check in on them, regardless of the hour. And if they are out and about, they quickly retreat when they hear or see me in the room. Don't let that put a damper on their value as pets, though. Very few snakes are bold enough to sit out in the open either in the wild or captivity.