Originally Posted by DaReKa
It depends on your bankroll. If you are aggressively moving up in stakes, you might begin a new limit when you reach 20 buy ins. So if you double up and have other deepstacks at the table with you, you are now risking 10% of your bankroll instead of 5%. The strategy isn't to prevent you from losing that 10$ that you made, it's to prevent you from risking a larger portion of your roll at once. So if you double up on a fish and other players are still >100BB, don't worry about it.
Ok, I'm going to expand on this theory just a little bit. The rule is to actually leave when your stack is more than 10% of your BR, not 2x your starting stack. If you're following BRM of not buying into a game with more than 5% of your BR, that doesn't mean that you will always be buying in for 5% of your BR. If you have a BR of $200 and the only game in you BR is 4NL, you would have to build it up to $20 before you hit the point that you should walk away according to those rules.
At the same time, if you're at a really great table and you can identify exactly what makes it a good table, then I say keep playing until those factors change. I was playing 3/6 live one night and was just about to leave when 2 guys came in, and one was stupidly aggressive and happened to be sitting at my right. It changed the whole dynamic into a very profitable game and I refused to leave until they did, so I was there another 4 hours. I was at a break even point when they came, and I had tripled my stack by the time they left.