I can only give my own experience as far as speed of gains but everyone will be different. Some of the reasons men gain at different speeds are intensity, proper healing, progressive training, proper form, and many other factors. If all men did all things exactly the same there would be some uniformity to growth, but this will never be the case. I gained 2" in length and 1/2" in girth in 6 months. I trained upwards of 6 hours a day, mostly manual and eventually with tools.