[Nasrudith]

In my experience/observation phone addiction and similar has several causes in addition to the obvious positive feedback loop. I know that in college looping music was used to cover up depression lack of motivation. Not healthy but it took me longer to recognize what it was.

Anyway avoidance of stressors is one which ironically is potentially situationally healthy but not always. I don't know the age of you nephew other than younger than you - using it rather than melting down about say an uncomfortable medical procedure is actually the healthier alternative. Obviously unhelpful in procrastination contexts of course unless tightly self controlled like a literal five minute break between an hour or so of studying. Or ADD/ADHD style attention regulatory failure loops. Borderline cases (no pun intended) might be depression if it proves helpful. Seeing a mental health professional for help is of course the right thing to do period.

Phones like many things are tools. It is helpful to look at the why of how they are used.