While it is important to take profits, most of the time you will lose money in gambling and you may forget about your bankroll to play more and engage in more aggressive gambling. The time period you have previously set for yourself to stop when you win a bet is probably not applied most of the time. I tried and lose again and again. I should stop instead of getting more tempted with the process of betting and losing more as a result of losing to reduce the continuation of further losses. I think the right time to make decisions during the game is when you mix the emotion with the reality and the outcome will affect you positively.
It's best to make that hard stop when you feel that emotion already dominating, instead of pushing your way that might possibly harm your finances, quitting is an option where either you are taking advantage of your luck, experiencing winning streaks should be converted to withdrawal profits, instead of pushing to continue getting that chance is not always be around.
Luck should wisely execute, never to fall with your greed inside as it will turned things most of the time into losing your entire bankroll.