In FR it seemed like 15k hands was good enough, but in 6-max there's a lot more varience. I was making like 20BB/100 over like 10k hands in 6-max while my brother who is just as good if not better than me was down after 15k hands! How many hands do you have to play in 6-max before you get a sense of what your winrate in the long run will be?