I think that there is a time to quit when playing blackjack even if you are good enough to get the edge. When I say quit all I really mean is to take a break for awhile! I think that you should quit if you are winning so much that you start attracting attention from the pit, so you will win less than the amount that gets you written up in the book of winners. From the pits point of view it is much more likely that you will be a winner for the day after 1 hour than after 10 hours of play if they findout that the opposite is true that you are more likely to win after 10 hours of play than 1 hour they don't let you play blackjack anymore. Which is why I prefer to keep my playing sessions to 2 hours or less. My game falls off a little bit when I get pit scruntiny because I get nervous. I also think that you should quit if you get into big a hole and lose to much money where you can't play at the level you started and don't have enough for doubles and splits. I also think you should quit if you are hungry or tired I have had some of my worst sessions playing while I was hungry and some of my best right after a meal!