In Wing Chun we do not talk in terms of Chi or internal energy or in terms of isotonic or isometric exercise. It doesn' t matter who learned from whom in the Wing Chun world. What matters is how much training you have put in, how good is your skill and having the right guidance. Remember, Yip Man did not sign any credentials. This leaves room for a lot of manipulative people to twist Wing Chun around.
Ignorance is no bliss.
With the external method of training Wing Chun, you will reach your limit very fast. You can train for ten years, then all of a sudden, someone with one year's training can match your skill. Ken said he still has to repeat the same advice to his students even after ten years. They have to be constantly reminded of the same thing over and over again like a broken record. Ken said the soft touch works.