I have had Jojo out for as long as a couple of hours but always in my hands or under my direct supervision. You can't leave the room for a minute with these little guys loose.

IMO I think that they enjoy being out of their tanks even if it is for just 15 minutes. Jojo will stay out of his hide and climb the walls when he wants out. If i put him back before he wants to go back he wont go back in his hide. When he has had enough he will go directly into his hide after i put him back. But keep in mind Jojo is a well established ball python.