Very often my youngest child is still signed in after several hours even if the TV was turned off (standby), we can be away from the television for hours and that profile is still signed in. This managed user does not have profile PIN (she is 4 years old and so need for her content).
But we have seen the issue happen every now and then for PIN required managed user profiles too but far less often. I would hate for my kids to turn on the television and load the Plex app only for them to see what filth the wife had been watching the night before and play it.
Solution: Have a setting in the PMS to force inactive managed user sessions in players to sign out after pre-determined times like 5 minutes, 10 minutes, 15 minutes etc.