I think it really depends on the table and the players. CardDead711 has hit the right note. If you are getting really lucky, you might want to consider crystallizing your profit, but if you are playing well, and the other players are exploitable, you might want to consider riding it out for a while. Sometimes, you can also keep playing, but set a limit on your downside, so let's say you started with 1.50 and have got it to 5.00. You might want to keep playing, but if you drop back to 3.50, leave with what you made, because you may have hit a downswing. there are always other tables, and sometimes going back to the original buy-in can start to build again. the same principle applies to losing at tables. Don't be afraid to leave a table that seems to be against you.