Fact is that why should you even leave in the first place lol. When things go rogue, what I believe is best to do is to stay around and study how things will go and you wouldn't even ask about when to reenter. But when you completely get out, you become more confused as to when to get in again.
Completely agree with you -- never get out 100%. Even when things are going well, I've learnt to take profit, but always leave a little something.