Frequency of masturbation is determined by many factors, e.g., one's resistance to transient sexual tension, hormone levels influencing sexual arousal, sexual habits established during youth, peer influences, health, intensity of the ejaculatory urge, and one's attitude to masturbation formed by culture.
The physical benefits of masturbation and having an orgasm or ejaculating creates heightened arousal while epinephrine courses through your body, producing the flushed face, shallow breath and post-climactic euphoria.
It is held in many mental health circles that masturbation can relieve depression, stress and lead to a higher sense of self-worth (Hurlbert & Whittaker, 1991).
In 2003, an Australian research team led by Graham Giles of The Cancer Council Australia concluded that frequent masturbation by males appears to help prevent the development of prostate cancer.
Masturbating frequently presents no physical, mental or emotional risk in itself, but masturbation can be used to relieve boredom or stress. In either case, as with any "nervous habit", it is more helpful to consider the causes of the boredom or of the stress, rather than try to repress the masturbation.
There is some discussion between professionals and other interested parties as to the existence or validity of sexual addictions. Nevertheless, there are lists of warning signs such as when sexual activity affects a person's ability to function in everyday life, or is placing them at risk, for example, of pursuing illegal or destructive activities. Very frequent and compulsive masturbation may be seen as a sign of sexual addiction
Some info. from Wikipedia.