If i play at a table and find after 30-40 mins im just breaking even after playing a few hand i leave thinking im not getting anywhere (this is actually untrue if ive had a bad run of cards staying even is nice for a bit of confidence)
On the other hand if i lose a buy in from bad play i quit. I dont think about it i quit for at least a few hours to try and first think about the hand, second forget what an ass i made of myself.
If its a beat (i called an all in this morning correctly only for the opp to catch one of his 5 outs) I continue after that as that is simply a beat in my book. But if i drop a second buy in after this i quit too, probably for the day and wait for my a-game to return.
A quick stat i found about my play is that curently im at 12bbs/hr where my standard deviation of profit/loss is one buy in up or down (or 100bbs).