Sparring is very important in order to develop basic spontaneous responses to various attacks. General sparring can be good for refining attribute skills such as, balance, rhythm, coordination, timing, actions and reactions as well as proper mental focus. However, it is important to determine the purpose for sparring. If it is for self defense, then the opponent must present realistic scenario attacks, rather than just spar against your own style.
We never spar against our own system of fighting. We train the secondary, or uke, to be a boxer, Karate or street fighter, not a Wing Chun Do or DeMIle JKD fighter.
We spar with open spontaneous matches or we do exercise sparring, which is to develop skills in different elements of engagement. Bruce Lee had us learn to spar in stages. First is Chi Sao, which is an exercise to learn perimeter lines and establish basic control within a trapping distance. Next is Slap Sparring, which is to refine controlling the opponent with a specific hand application called Palm Phon Sao. Then there is Wrist Slap Sparring, which limits you only to defensive wrist contact of the opponent arms. Lastly, is the art of free style Phon Sao or the art of Trapping, which is discovering your personal way of controlling the opponent