You need to separately select the “Send Alerts immediately” checkbox to allow the Security Event mail notification feature to notify you when someone attempts to visit the websites you blocked. No other user can change the schedule you assigned through routerlogin.net  until or unless he doesn’t have the login password of the Netgear Router login window.

https://19216811netgear.net/netgear-ax6000-12-stream-router-setup-guide/ 

https://19216811netgear.net/netgear-r6100-ac1200-dual-band-wi-fi-router-routerlogin-net/