I don't think you should fight in any situation. Fighting is always grouns for retaliation. It works in almost all ways of life. Like rival gangs killing eachother members a day later that person get a drive by done on their house. Schoolyard rumbles are especially bad because the most common fights are with the popular person, so all his or her friends will jump you. I've had to deal with that before. That's why I think it's wise to avoid fighting by all means neccessary but if that person is to attack you to play the defense or try to neutralize his or her attacks.