So your issue with the "box" idea is that it doesn't go far enough

No. My issue with it is that it only pretends to solve the problem.

As stated in my original reply, my idealistic solution is to keep using your phone but gradually exert mindfulness and discipline to retrain you relationship to it. This too me is the quintessence of self-control.

However, as binder said, the idea of trying to moderate something you're so deep into sometimes just doesn't seem possible. And it's futile to attempt something you don't believe is possible. In those cases, I think that abstinence is an acceptable secondary solution.

I don't believe it to be as good as my ideal solution and I don't think it's an ultimate representation of self-control. But if it stops a person abusing something and makes them happier then I say 'go for it'. Furthermore, I believe abstinence can be gateway to reintroducing something back into your life once you've had space away from it to reset. From there you can then practice 'true' self-control.

In comparison, the box idea is a middle-ground that accomplishes nothing. It doesn't teach you to use something responsibly nor does give you enough space from it to reapproach it with a newfound mindset.