Keeping record on your gambling activities only helps you to know how much you may have gambled with within a certain period of time, and likewise how much you may have also lost, but just like O.P said, to me, I don't see any need why anyone should keep such record, because it's just a total waste of time, because either keeping record or not, it won't stop you from losing or neither winning a game, in as much as you are gambling responsibly. Because I think such record is meant to be kept for people who are addicted to gambling, so as to be able to regulate how much they waste on gambling.

But on a general sense, it's literally of no value to either the gambler or casino.