We've done things where we have him earn more time by earning points and using those towards screen time but nothing really stuck. Everything became an argument and when he has a different schedule one day like having to go to piano lessons or basketball he'd lose out on some screen time even though he had the points for it and that did not sit well. He just does not like anything outside of a regular schedule but unfortunately with different things going on it's impossible to have the same schedule every day. Plus he'd rack up so many points that he'd have enough for hours and hours every day and he didn't think it was fair that we were limiting it even though he had the points for more time. It was just a headache.
We tried Khan Academy and I thought it was great but he used to skip tutorials because he wanted to figure it out on his own. Then it would be too hard to figure out and he got frustrated and gave up. In everything he does, he wants to skip the basics and jump right in but then when he gets to a part where he needs the basics that he never learned, he gives up.