I used to hear this a lot from one of my better bosses. I agree with it. It is, however, important to capture "planning". Any form is fine, whether scribbles or a list or a picture of a whiteboard. Trying to organize the raw info was usually a waste of time, but having it accessible as a reference wasn't.
They have a good lists of mind sweep / brain-dump triggers  that I think benefit everyone even without ever doing everything one writes down.
General George S. Patton, Jr.
No plan survives contact with the enemy.