Why does everyone always talk about how easy it is to uninstall K9, or access sites? That’s basically irrelevant.
It is designed for someone other than the “filteree” to keep tabs. So if your kids uninstall or access the wrong thing, you’ll know. Will they davka try to go somewhere inappropriate knowing that you’ll know about it very soon?
And if it’s for yourself: if its so nothing should pop up, no problem. If its to stop a nisayon, then someone else obviously controls the password/email, and should check your record occasionally.
For most users, it works fine.