I don't have school agers but I have an almost 4 year old that copies the younger ones like crazy!! When I send the 2 year old to use the little potty the 4 year old says she needs to go too. I was sending them both at the same time as the 4 year old uses the big toilet but then I caught on she wasn't going, she was just wanting to copy the 2 year old. So now I tell her she has to wait until the 2 year old is finished and out of the washroom before she can go in and I'd say 9x out of 10 she never does end up going in because she never truly needed to go anyways.

I wouldn't forbid a child from going but I would say they can wait 5 minutes. If they truly need to go they will tell you. They are school agers and are capable of holding it for 5 minutes.