My son is an avid gamer and can play video games for 8 hrs+ a day. My wife tries to set limits, but this just creates a lot of conflict.
The good news is that he prefers playing games with his friends online. And he likes playing gorilla tag and other occulus games where he is moving around so much he actually works up a sweat. When his friends are not online, he is not as interested in playing games, but will want to watch youtube videos instead.
I played a lot of video games and watched a lot of TV when I was a kid. But it was mostly just a time suck when there wasn't something else to do. I don't see screen time as being a threat as long as it is just something kids do instead of watching TV and do it with friends. But if they play by themselves and have no other interests, that is something that requires some intervention.
I think it is very important to make sure kids have activities and interests outside of video games. It is very difficult to get kids plugged into different activities and sports these days because everyone is pushing their kids to be hyperspecialized so they can try to get a college scholarship. My son plays club soccer and is ready to quit because all the kids on his team want to do is try and 1 v 1 on seven different kids on the opposing team and score a goal single handedly. But he also plays golf and is into rock climbing. Rock climbing is great because he can do it on a rainy day.
So, the answer to excessive screen time is to make sure your kids have other activities that they are interested in doing. It is hard because as soon as kids get into jr high there are fewer and fewer activities and sports that kids can do just to learn and have fun. But you just have to shove your kid out the door and get them to try as many things as they are willing to try. Hopefully, something will stick and get them off the screens. But the reality is that kids like playing video games and kids should get to have some fun. Cutting off screen time to force your kid to read Wuthering Heights or do math problems to get ahead on their test scores just isn't right.