See, I was thinking the same thing (3 being good vs 4) but I felt like I'd seen 4 being stated as what was recommended but the two I have are already so frickin bright, lol. Still finishing a grow with a Mars 300, so I still haven't been able to experience the full autocob goodness but soon! Once I get my next grow going I'll be training them good and early w/some topping and LST. This is still my first grow so I was a little timid with the LST and have definitely seen that I could have been much tougher on her.
Just start bending her after she has her third set of leaves and take the main trunk in any direction it wishes. Take the first two lowest branches that develop and direct them in the shape of a v opening away from the main trunk in the opposite direction of the main. The next set go back but wider like the wheels of a spoke. If you can get 8 solid branches spread out this way and hold the main down below until they are well into stretch you will get a heavy solid crown with ton's of bud. The more flowering points you can train and hold in a 6 inch zone in the top of the canopy the more main cola's you will have try to develop. Turns out to be a field of pineapple grenades. Usually 4 or much more ounces per plant.