I used default profile and added calendar for 1 kids, it worked well
Then I created a new profile for parents without calendar, added parents’s laptops and phones in device for all day access, it works well
Last I created a new profile, added my 2nd kid’s ipad in device, set up a calendar for him, to my dismay, I found he has all day access, instead of the periods in the calendar.
The plan is to see if the calendars are effective. If not, we’ll find out why and fix the setup. If yes, then your son might be using some trick to get around it and we need to figure out how to block that.