My computer has two “Users”. Half the password for Administrative User I know, the other half my kids know. If they don’t put in their half, I can’t use the internet. This usually
means that until around 5:00pm, the internet cannot be used, except for gmail accounts, since the other “User” that everyone knows the complete password for only allows gmail.
K9 internet filter also allows one to specify hours that internet cannot be used. So between 11:00pm till 7:00am, the net usually cannot be used. That too, half of the K9 password I know, and the other half my kids know. If I ever activate after 11:00, I would only allow it for 15 minutes, so that always stops me from using it longer.