Karl Marx wrote a short summary of every book he read and many scholars and successful people refer to note taking as the secret of their success. I once shared a platform with Richard Branson, where he put his entire business success down to his lifetime habit of taking notes. Apart from being dyslectic, he made the simple point that we forget most of the good ideas we come up with, so taking notes prevents forgetting. He attributed almost all of his business ideas and successes to note taking.
I am also an obsessive note taker and have dozens of black notebooks which have helped me learn and plan over the years. I am often astonished, when speaking to large audiences of learning professionals, how few take notes, when the forgetting curve has been established, since Ebbinghaus in 1885, as one of best known and researched pieces of learning science.