Is it better for children to have a daily internet limit imposed on them?

I’ve been interested in this question, due to as a child, I would always have 1 hour of tv or an hour on my dad’s laptop to play games. Some people in my life did not have any limit imposed on them, and we have very different academic habits. I want to figure out if children’s internet usage effects how they perform in school. I expect to find out that the more a child usages the net, the more likely their grades are lower, but I’m not too sure in my inference, as there are many educational tools on the internet that now exist.