We mostly keep the cats inside our house, but sometimes, when the weather is nice, we let them out to run around and whatever. When they want to go in, they would go to the litter box, do their thing, then go back outside.
I think we kept them in the house for too long.
my two cats love to be outside in moms garden, but they are well trained to the prompt calls of "INSIDE!!" and they promptly run inside with no problems.