I
don't think that is a very good rule to move up when you've made 10 buyins. Personally, I feel comfortable playing w/ a
bankroll on the site of only 10 buyins, but that is because I've always moved up when I was killing the previous
level.
I think the biggest rule is to move up after you have been consistently beating the
level you are on for at least a couple months. JMHO. Even then, only move up if you are confident you can beat the next
level. I also recommend spending a lot of time watching play at the next
level.
I think confidence is so important, because when you move up, you may go directly into a
downswing and you
don't want to get discouraged there if you know your playing great poker.
Another good thing to do is
set a reasonable limit that you will lost at a
level before moving down. For example, if you want to move to 1/2,
tell yourself if you lost 1600 dollars you will move down and build up again. That isn't a terrible strategy.