Mathematically speaking, if you knew you had a worthwhile edge, the right time to stop gambling is never-- like a casino.. or a Quant system. Even then, if things go too far amiss, it is wise to take a long hard look. Successful Quants have even gone so far as temporarily "unplugging" their systems. (Exception: some types of trading may only do well durring certain time periods, so obviously...) The more subjective and less defined an edge is, the more it may make sense to gamble longer when winning. And to quit earlier when losing. Poker analogies that do not exactly hold: Most people make worse decisions when losing lots of money, more money is usually made when the game has an unusual number of bad players, most people play noticeably worse when tired or upset, etc And you can often flip ideas around: Most people play better when winning and not tired, etc. And is something unexpectedly has changed that perhaps you do not see; well.. .