Personally i used an internet content filter which also enforced time limits.
the kids had a limited data plan and used the house internet. once it was off they could burn up their data for the month, but that was a choice they made.
as they became older and more mature the rules were lowered. Longer internet times, less content restrictions.
People thought i was weird at the time, but now the kids are adults they said they would do something similar to their kids as it was what they needed, not what they wanted at the time.
