Player notes\reads

[Stack]

It is worth taking notes ONLY IF you can exploit your opponoent's weaknesses.

This guy is passive and straight forward after the flop.
That guy donkbets with a weak-made hand like middle-pair bad kicker on the flop.
This fish just can't fold an Ace overcard until the river and he also calls down any piece of the flop.

If you don't know how to exploit the weaknesses above, don't waist time taking notes. Either open up another table or go back to chatting with your friends. Take notes if you can exploit them.

If the first guy (passive and straightforward) is 3betting the turn, let your middle-pair top kicker go if you don't have odds to draw.

If the second guy donkbets, raise with your overpair or pop him on the turn, and if you have only overcards, you are probably drawing.

Against the third player, don't forget to value bet.

Take notes if you know what adjustments you have to make to exploit the new-found weakness.

This post is intended at beginners (like myself). Better players can exploit many more situations and note taking is more +EV to them.