I think he had a Rich Froning size build - around 5'9 and 190-lb, except leaner. He trained for "balance" even though in reality he did everything he could to grow as much as possible, but just had the genetics to be 5'9 and 190-lb, but FLEX magazine created the tale of Zane training for balance when he just did what everyone else did. Oh, and I also copied this post from someone else on here. 
I could get my legs bigger if I wanted to, I just don't want chaffing thighs, my legs grew very easily when I started training.
My upper body struggles to gain size.
Legs for me now is
6 sets hacks with 30kilos max
6 sets leg curls with around 40kilos
5 sets calf raises with around 90kilos
3 sets stiff leg deadlifts with a 10 kilo plate.