build the necessary balance for good kicking power, get the stretching done to let you have more "arc" of hitting (especially with kicks) have a feel for correct distances, be able to block, evade, feint, set up the guy for a particular technique, or recognize that opportunity when it presents itself. This is if you train hard, for at least 1 hour a day, at least 3 days a week, no more than 4 guys in the class, with a truly good instructor. Anything less is a waste of time and money. Large classes just teach you bad habits. The instructor can't get around to correcting everyone's errors, you see. So they practice WRONG, inculcating stuff into their "style" that just gets them into trouble.