this from the second article :


Qi Mag: You were with Yip Man for a long time, did you notice that Yip Man's style changed as he got older?


He didn't change much, just got lazier! (laughs). When he first taught Siu Lim Tao, there was no Gang Sau in the 3rd section, but Jum Sau instead. But after I had a serious fight, the Jum Sau was changed into a Gang Sau. In the fight, the other guy was a lot taller. I'd hit him so badly in the face that he couldn't see, so he knelt down and covered his head with one hand and with the other blindly hit out. I went to block with a Jum Sau, as in the form, but the punch went really low and still connected. I was hurt and had to take a step back, even though the guy didn't realise he'd hit me. Eventually I knocked his teeth out, and he collapsed, so l won the fight. When I went back and told my teacher what I had found out, he told me that when he learned from Chan Wah Shun, Chan Wah Shun taught Gang Sau in the form, this was because Master Chan was tall, but when Yip Man later learned from Leung Bik, Leung Bik taught him to use Jum Sau because of the sequence in single sticking hands. But after this incident, Yip Man changed the Jum Sau back into a Gang Sau.


many dont use jum sao in dan chi-sao ...evolving into the wrist or 'DE'-volving [is that a word ?] iow going backwards when trying to achieve a strike that can do multiple functions in one beat...using tan & Jum in dan chisao....no wristing