Honest question, how do you keep a cat indoors at night? We used to call them, but sometimes they wouldn't show up. That meant you might see them the next day, or never again. One little poofy grey cat we had disappeared for a week before turning up soaking wet and meowing frantically. Cats are quick and can make pretty good distance from your house, so when you're calling them in for the night, they could be literally anywhere. They also like to hunt at sunset, so might just ignore you on purpose.
That's my experience anyways. I think some of the other comments here are right, that a limited outdoor space that they could enjoy but not escape from would be ideal. I don't have a yard so my cats are indoor only. I did try to leash-train the smarter one but she was not having it.
edit: we would clang their food dishes and shake the food bags. Calling them in for the night was also feeding time. My experience was that despite this they wouldn't show up sometimes.