Reading notes is only necessary because of how lossy human memory is. Reading notes doesn't give you new information, it just reinforces memory paths ... which will fade and you'll have to read the notes again later unless you frequently apply the knowledge, which again reinforces those paths (but lossily, so the bits of information not repeatedly used will fade, and you will again have to read the notes if you need those bits ... or just to re-mind yourself what they were).