That would still reduce ther exposure by 1-2 orders of magnitude, which is perfectly acceptable.
IMO the problem is twofold: first, younger kid's brains are not developed enough to deal with games and social media that are intentionally made to be addictive. Heck, even a lot of adults have issues limiting their time. Addictive games and social media should just be forbidden under 16 years. Currently our government has only issued a recommendation, which does nada. Second, teachers and parents need to be educated better. Many have no idea that these addictive apps are an issue or just don't fully realize the damage they do.
But you know, I find it frustrating that the people we're talking to clearly have no experience with the subject but they come in here and state with confidence they're opinion on something which is for them a hypothetical. They don't know what's going on.
Age verification doesn't solve that though.
And not only that but some of those times are dinner break, on a school campus with a thousand other kids and barely any supervision. Even if phones are banned, it's easy to hide one and for a child to be showing their friends unhinged stuff they found on 4chan.
And some of those times are on a bus carrying at least 50 kids when they're 'supervised' only by a driver ... and so on.