There is allot that goes into why and how Penis Enlargement works. But I will try to keep it simple. Length comes from two main sources 1.) Lig Stretching, when the suspensory ligament (Band of tissue that holds the penis up against the pubic bone.) are stretched within the body allowing the penis to become longer as more length is added to the stretched ligament. Some call this internal penis.
and 2.) Stretching the external penis or Tunica. The tunica is a inflexible tube that surrounds the three spongy chambers. During an erection the tunica becomes tight and restrictive giving the penis rigidity. Tunica stretching or enlargement is a very slow, arduous process as it contains less than 5% elasticity. When we stretch at higher angles, that put little pressure on the ligaments, most of the intensity of the stretch is absorbed by the tunica. The tunica some see as an endless source of length gains.
Girth enlargement happens when the corpus cavenosum, the two chambers on either side of the penis that holds blood in it's spongy tissue during erection, are filled with blood beyond there capacity. It is important to understand that this tissue is housed in the tunica so the same slow, arduous, rules apply. Girth will be temporary swelling until all of the tissue affected deforms permanently to hold the increased blood during an erection.
I have always tried to be forbearing with girth work. I keep things uncomplicated and intense. My only goal, when training girth, is MAXIMUM EXPANSION. What I try to do is to get temporary swelling beyond my normal erection circumference each and every workout. Eventually, as it has happened for the past 4 years, temporary...slowly but surely becomes permanent.
In flaccid length exercise it is difficult to over train the penis. This is due to the extremely small amount of muscle present in the penis. With this in mind I see length exercise as the more the better. I do a extremely wide array of length exercises being sure to spend time on both the ligaments and tunica.