The last time I did so in a thread like this I got into trouble.
Frankly there is only one parental control worth a damn and that's for a parent to separate the PC and the gadgets completely from the teenager during the periods they want their teenager to not be using them.Harsh I know but it's the only effective method I'd trust.
It's my experience as an educator having covered IT lessons in secondary schools is that teens are extremely smart and are very adept at getting around most blocking systems.