Account is not blocked in case of exceeding hour limit

Hello,

I have allowed one hour per day on computer for my sons. I have chosen this parameter in Norton Family.  But Norton Family doesn't block when they exceed one hour. Yesterday, my oldest son managed to use computers during 2 hours.

I have tried to understand. Norton Family displays message when computer comes to the end of the hour. At this time, I think my sons stop the Windows session. Then, they enter again in their Windows account. I assume that Norton Family does not activate immediately. As a result,  my sons keep on using computer.

Thanks for your help