There's a time to plan and a time to do, and those times don't usually overlap.
At least for my dull mind, there's not enough mental bandwidth to do both at once.
On top of that, the mind is a tricky animal. If I'm at the gym, in the middle of a workout, and my "planning" brain switches on, I can find all sorts of reasons why I "shouldn't" finish the workout. I'm too tired. I might be getting sick. I don't have much time. Is this workout even working? Maybe I should try a different one. It would feel so good to stop right now.
If you're having trouble practicing, I bet one on reason is that you are overlapping planning and doing.Want to learn piano but don't know where to start? I've taught hundreds of happy students! Click here for my free beginner lesson course.