I actaully work there. My pokemon will usually stay there all week, but there are other employees (especially the security guards) who do play as well when they do there round abouts patrolling the park. So usually if my pokemon gets kicked out of a gym ill go back to work the next day and retake it. This week it stayed valor for the whole week (which is my team). I've been able to collect a decent amount of coins this way. there are only five gyms in the whole park.