My question is; where have you been! lol..I recognize that name from when I first signed up on CC, I think we started around the same time.
Anyway in answer to your op;
I personally play regardless if I cash or not so long as I feel emotionally ok. So long as I know I'm making the correct decisions and feel I'm playing my A game, there is no reason to stop playing. Results will come if you keep playing well.
There are some days I can feel after my first 10 games, today is not a day I should be grinding, so stop loading and finish of my current games and be done for the day.
If you start losing a ton and realize it has effected your play, you really need to stop playing at that point because like with you and many others, you go on an lose a ton of your BR.
Basically to avoid it happening again, quit when you realise your A game has now turned into you C game.