>you're allowed to leave gyms at any time
....why? What point is there in even doing one if you can just run in and out of the poke center when your mons are low on health? There aren't even wild encounters to pose any sort of risk. Gyms should reset upon leaving, otherwise the whole 'challenge' aspect of them is thrown completely out the window. Maybe even have a small admission fee. I mean, these gyms need to have some way to make money, right?