For a child who already finds sustained focus difficult, screens can be a mixed bag — genuinely calming for some, or overstimulating and hard to transition away from for others. What works varies a lot by child, so it's worth paying attention to your own child's pattern rather than following a blanket rule.
Transitions off a screen tend to go more smoothly with a warning — "five more minutes, then it's time for dinner" — than an abrupt stop. A visual timer can help make that countdown concrete for a younger child.
Some families find that screens work best as a scheduled part of the day (right after homework, for example) rather than something that fills every spare moment, since it gives structure without needing to negotiate every time.
Not all screen time is equal — a highly interactive, fast-paced game affects attention and mood differently than a slower show or an educational app. If evenings feel harder after certain kinds of screen use, that's useful information worth adjusting around.
There's no need to eliminate screens entirely to see a difference — often, small changes to when and how they're used make more difference than how much total time is spent.