I only play about 2-3 tables at a shot. This is for a variety of reasons, but one of those is because the notes I'm taking are invaluable.
But just an example of some notes I've taken recently:
1) Minraise PF w/ spec.
hands (44, A3s)
This play would raise to 2xBB's everytime he'd play a speculative hand. So I just got in the habit of re-raising him huge
2) c/c station, 2nd pair enough to stack in raised pot
This guy check/called me with 2nd pair on the flop on all 3 streets.
3) Calls PF 3-bet /w ATs. Loves s00ted cards. Will chase flush.
This particular villain called my 3-bet with AK with AT suited, so obviously if he has any semblance of a hand he's going to try and see a flop no matter what the cost.
So I just try to quickly take down features of their play I can exploit.