BROKEN RECORD STARTS PLAYING:
The method at which you GROW best might be determined by the type/density/ratio of MUSCLE FIBERS in your body. I NEVER grew training like a BB the way I grow training like a powerlifter. Of course, I was a sprinter for many years, and it only makes sense that I would excel in sprinting BECAUSE of the the muscle fibers I have. If you have "sprinter genes" you might just grow better this way too. I have been training this way most of my life. The one year I trained like a BB, progress was slow and frustrating.
That said, Westside incorporates strenth, speed, low rep, high rep, and HIIT. Little bit of everything.