Yeah, I feel like there's some crucial undercurrent here. I'm wondering if their mother was so "laid back" that she made LW feel insecure, and the rigid schedule is as much about LW's own anxieties. Which could mean that the way LW describes their son could be a mixture of knowing their own kid and some projection about how lack of structure affected them as a child.

This is, as always, total conjecture, but Grandma's behavior makes me suspect LW had a chaotic childhood.