Not even necessarily for making money but simply for learning how to read an opponent at a faster rate.
I've only played about 3600 hands of 10NL HU since returning to AP. While I've managed to crush it for nearly 55 bb/100, the affect it has had on my confidence in 6max is quite amazing. I've been able to adjust much much faster to my opponents. My reads have been much much more accurate. As a result, I've been able to adjust my cbets based on my perception of my opponent's range which leads to getting better more value when I'm ahead and limiting losses when I'm behind.
Combined with tourney results, rakeback, and reload bonus, I'm up about 9 times my initial buy-in from this past Sunday. I'm thinking I'm going to run the BR up to $1k before I jump to 25NL just for comfort sake. We'll see if I can be patient enough to work towards that goal.