That's a good question, but regardless of what the growing method there are still other factors that contribute to yield and are out of a breeder's control (i.e. grow medium, your experience, etc.). Those figures are only estimates, and IMVHO are not grounds to base a seed buying decision on. Hope that helps and happy hunting
My friend has the biggest shrub you have ever seen and its many times over the yield that the seed shop said. Secret is chicken shit.