From what I understand, leaf count has to do with Sativa/indica dominance. Straight indica usually has 3-5-7 fingers, blends usually have 5/7/9, and pure Sativa can be up to 11-13 fingers.
Some of the pure Sativa I have grown have had 7/8 fingers by the third node/second week, and 9/11 within a month, and the current indica blend I'm running at the moment started out with 1 finger, went to 3 on the second node, five on the third, and has popped a few 6 finger leaves on the fourth.
At 21 days, fat monkey auto.
I could be completely wrong though.