Well, I personally feel 40min/day for a 7yo is bordering on too little. Personally I had mostly unsupervised and not strongly limited access to a computer since about 9, and I definitely owe at least my career and my English skills to that. I mean - how can one expect a kid to learn to do anything creative/productive with technology, if one gives them so little time that learning and creating isn't a viable option?
It's tricky to strike a balance. I'm on the computer for literally like 14 hours a day so I'm def not a good example. As a kid I had a lot of access too. I'll keep in mind your thoughts.
I switched my kids to "no media during weekdays" and after about 3 or 4 days of withdraw, it's much, much better. now they have time to play, do homework, and practice piano during the week without the constant complaining that they used to exhibit.