Boys have school many nights until 9pm and Sunday until 3 or 4 pm.
Kids need some time off. I know of Boys who have a Chavursa during RECESS at School.
Recess is not meant for a short Chavursa, Its meant for a BREAK.
If you want to say Bittul Torah, fine, but then everything not learning is Bittul Torah. Is Eating and Sleeping Bittul Torah.
Rav Nissim Alpert once had a tooth extracted because he did not want to “waste” the time in the dentist chair to fix it.