Every node produces a flower/bud so the more nodes in veg however long that is or even in flower is going to give you bigger buds including all the environmental factors mentioned above. And the mention of good genetics is also very important, I concur with that. But I do disagree with the clone of clones producing less, genetic quality is not proven to be lost in cloning down the line, I feel that is a misconception although it should be taken into consideration that generally clones are flowered at a much smaller size hence the lower resultant. Or at least that is what I do and get, 4 inch rooted clones into a 8 week flower cycle producing a single cola of around 14-16 inches and 0.8-1 oz. dry.