My paretns don't stay; our gym prefers it if the don't. There is a window and some parents come, but usually it's just a dop-off, pick up thing. My parents just drop off and pick up at the door.
The coaches dont encourage parents to stay. They dont ask parents to leave but no one gets an invitation to stay. Also, if the kids are paying more attention to the parents(ex. waving, making faces) the coaches will give a warning that they will be asked to leave the gym for the day.
My daughter is in the gym 16 hours so I cant stay the entire time. I usually stay the first hour and then I leave.