In the beginning, when we are practising Chi Sau黐手 with a partner, we should face each other square on. This means shoulders to shoulder, chest to chest face while we roll hands, in particular, our stances should be square on and our feet shoulder width apart. I have come across people who like to put one foot forward while they Chi Sau. This is the wrong position because in Wing Chun we must train both sides, this means we train both hands and both legs equally, so both legs must have equal weight on them. In terms of our health, this is good for our legs and we will not develop one leg so it is stronger than the other leg. If we always put our weight more on one leg, then we will eventually have a hip problem. Today we can see many people who have hip problems. If people study Wing Chun correctly, then they should not have back and hip problems.
Standing with your weight on one side also affects you internal organs such as your kidneys and lungs. In the long term it will mean one of you kidneys or lungs will be stronger than the other. In terms of Chi Sau it means one side will be more forwards and the other more backwards and then your opponent can pull that forward side and make you lose your balance.