I always try to take out my starting stack but sometimes it is a bit hard. I guess it depends on my mood at that given day and if I feel like I'm "ready" to lose what I started with or if I have a set goal in mind. Also depends on how much I win, if I only doubled my starting stack I don't think I would. 3x-5x increase, maybe I'll consider it. 10x increase and I for sure take out what I started with.
Once you violate your own rules that will be the start of frustration as it cannot be avoided that sometimes we will blame ourselves for the wrong decision we made. If we based on our mood that is not right if you are really aiming for profit, but if it's for fun then it's the best thing to do, always gamble to make yourself happy.