I don't think it goes based on strains but the way ot's produced. Commercial growers probably don't even know what strain they're growing as they're in it for cash, not quality. They're usually large scale grows, so that's why you get seeds sometimes, as going through hundreds of plants, it's easy to miss a male.

I couldn't tell you though. I'm guessing they get clones. Faster to grow, no males. What strains though, who knows. The quickest ones to grow and the highest yeilders I'm guessing.