***BUT THIS PART OF YOUR STATEMENT IS UNCLEAR? What is the reason for the differences between William Cheung's movements and those of Yip man and Ng Chan?[/QUOTE]

if you are not teached the best way ,or for the time you need to accomplished youself;
so ,if you were too young and not enough mature to undestand the system
or if you are missing some technics ,you will try to substitute one way or another.
Your physic as well will influence your technics ;
if you tall ,short ,or slim or fat ,with muscles ...
See what happened with people who have implemented wing chun with ,grabbling ,fighting on the ground ,chi kong,shina ...
they go far from the authentic W C
BUT at the same time if when ,fighting against another style and as a result you see that you are not doing more than kick boxing ,you can tell yourself that you have not been teached wing chun
and please this is not a way to offend people who train serously and honnestly ,but just to try to give you an true picture of the reality of a style that not everybody can have access to authentic one
but this can help you to question yourselves ,to ask you question about you training and the way to improve it
let me add something ,i have been during a while the only student of ki ping pun ,i neither paid anything ,because himself when he was leaving at ng chan house didnt pay anything.the only price that i have to provide was only to show motivation and to train serously but i receive an very classic teaching ,i neither practise repeating the same sequence of movement 20 times that an different sequence.
i had to get familiar with a concept attached to each movement and that to be free of the movement
and this is already the base of wing chun because if you train several time the same sequence ,its already not anymore wing chun
wing chun try to teach to ready for any kind of situation that you will try to drive yourself but if you plane something too precise during the training you become dead and your technic is mechanic not alife like it should be
there is neither the two same situations in fighting
i understand that people who live from the teaching has to be abble to provide something to motivate their student but training in a mechanical way kill the system and the ability to improve above the movements