On I could be wrong about this, but I think I've heard of studies on this. And it was determined that excessive masturbation can have physical/psychological pitfalls.
When it takes on the aspects of an addiction, and one has to do it to function. When one begins to think less of themself / guilt, that they retreat from social interactions and become overly apologetic about everything in there lives.
If this isn't happening and you're not getting arrested for it or skipping social events to pull one off, just listen to your body. Quit when it is painful, seek medical help when necessary, and you should be fine.