I spend at least half an hour a day doing something will Milly outside of her cage. I have an odd 3rd shift work schedule, so every night is different. On nights that I work I will get her out, let her crawl around on me, feed her a couple mealworms, try a new treat once in a while, and cuddle for 10 or 15 minutes. Some days, if I'm awake and happen to hear her moving around in her cage, I'll take her out for an hour cuddle session while I'm on the computer or relaxing when I get home from work. On nights that I don't work, she gets her treats, then I let her explore for a while, and when she gets tired I lay down and she sleeps on my stomach for an hour or three.
I really just go buy how Milly acts. She is a grouchy hedgehog. If I notice that it's a particularly cranky day for her and she's thoroughly not enjoying my company, I'll spend half an hour or so with her. If she's curious and happy, it's much longer.