I also top at the third node but.......you must have strong genetics.Not every auto responds the same way to topping and LST. The best auto come from Spain,almost super autos.After topping,I remove the first and second nodes then pin that lady all the way to the dirt,being careful not to break the stem.As each branch develops they to are pinned down and each consecutive branch until she starts to flower.Now each branch grows straight up,allowing excellent light penetration.As a example,I had a total dry weight from one plant of 166 gr. and that was not a super auto,but a blueberry kush auto from Nirvana.On the other side,a Super Skunk auto from the same breeder almost died every time I tried to train it.Now I have a plant with about 20 tops no bigger then a pencil....live and learn.Do your homework and never be afraid to try something new