Members of IAWCF training at a boxing gym in Norfolk, Virginia.
The training consists of forms, movement exercises, and a lot of one on one drills and Chi Sau to help the body memorize techniques. Conditioning exercises are important, too. Physical strength actually is a factor.
Training becomes more intense with more experience. First is accuracy. Then power, and then speed. Power and speed are useless without accuracy. By the time you reach a level of confidence to start sparring, you should be good at all of these. You will move quickly, efficiently, and effectively without getting hit.
Wing Chun techniques are often simultaneous. We cover an attack while attacking. Some techniques retreat and cover, and then attack.
Chi Sao is an exercise to train covering. It is not sparring. No one really fights like that, but it will give you better sensitivity to your opponent's movement..