Sorry to object, but I need to clarify a point here...
I work as a personal trainer. I have studied anatomy, biology, physiology, and chemistry. I think its safe to say that I know a little bit about the ins and outs of the human body...
Now... Is the penis striated muscle (skeletal muscle)? No. Which means the tissues that make up the chambers of the penis have no voluntary contractile capabilities (but the PC muscle is, which can help shunt blood into the arteries of the penis). The tissues of the penis are smooth muscle. And any type of muscle tissue can grow once it has been stressed and allowed a recovery, albeit everyone has their specific needs. All types of muscle tissue need periods of lowered intensity/rest to enable positive adaptation (tissue growth, increased cardiac output/strong, lower resting Heart Rate). Likewise, the heart... if you continuously train it intensely without rest, a heart attack would ensue - possible from neuro-muscular failure.
Maybe you should try to take a day off every few days of intense training. In most regards, If you over-train/over-stress the body, it will cease to grow. Several theories exist for this phenomenon... some of these theories indicate a predominance of catabolic hormones that impede protein synthesis (tissue growth).
Just some thoughts...