well you can implement a system if you like. like move up at a certain point and move down at a certain point
for example
i'm going to move up at 100 buyins and move back down if i have under 40 buyins.
But really, it's also a matter of are you beating your current level over thousands of games, and do you expect to be able to move up in skill level and be able to achieve a decent winrate. So be honest with yourself, make sure you know you can beat the particular level you are on before you move up. You don't have to do this obviously, but it's something to consider as your skill level will dictate what stake level you can beat, there will come a certain level in which you will be losing money, for everyone that is differant, but once you get past the $7 games things get a little tougher and it will take more skill/work to be able to beat the games.