How much planning needs to go into a day? Am I doing things that really matter? How do I determine what those important things are?

How many of us like planning? What impact does planning have on our personality type? What impact does our personality type have over our planning? Can all personality types plan effectively? Can all personality types enjoy planning?
These are profound questions, that needs to be answered. We need to negotiate with ourselves about the task of planning.

Without planning everything tends to move towards chaos. However, there needs to be some form of chance or serendepity to come to play, periodically, to shake us out of the rut we fall into.

Effective life is finding a balance between planning and random chance/serendipity. For those who enjoy planning, they need to learn to enjoy chance and randomness and those who enjoy flexibility, randomness and serendipity, they need to learn to enjoy planning. It is not "either -or". It is "and".