I agree with you but then I don't think you can call this deliberate practice, deliberate practice is not just sitting down and pushing boundaries, it's also having a clear path. In programming (since you said Alan Kay) sitting down and knowing precisely what you need to do in order to get good is very rare. Here everything is displaced - once you know what is good, everything is downhill. The problem is always overcoming X - that place where you don't know where you are, you don't know where you are going and you somehow need to get to your destination.