...it depends on the strain, I found that my Sensi Seed's, Big Bud get better yields with around 35-40 in each 3x3 footprint, scrog style because they tend to branch out alot. My GHS, Trainwreck seems to do awesome with 20 - 25 in the footprint, they make huge colas!....Barney's Farms', Blue Cheese 20 - 25, this strain bushes out alot and stays very short.
...these are the only 3 strains that I have found worthy of mass produce'n, been through roughly 30 or so strains. I have Vanilla Kush, and LA Woman germ'n now.
...yeap, those are 3" netted pots inside of 6" x 6" x 6" square pots, hydroton/high silica rocks as medium.