I did a search and found his styles site and as I thought....... it is a relatively new system. here is the site link
http://www.angelfire.com/fl4/kskf/copy_of_index.html
after reading the history of the style I have found that they do indeed hit the wooden dummy. and I quote
powerful projection energy developed through impact hitting on the mook jong (wooden dummy).
This would lead me to believe that they must make the arms thicker and stronger to accommodate their heavier hitting. Even on the regular traditional dummies you can hit pretty hard but if you break the arms you've gone too far. I have seen styles of Wing Chun that use the dummy for conditioning the arms. Augustine Fong for example has a five strike conditioning drill he performs on the dummy....... but only uses minimal power.... just like iron palm training to slowly toughen the limbs.
There are principles that grandmaster Ip (Yip) Man himself laid out before all of his students. they are as followed:
Guard the Center
Face the Point of Contact
Economy of Movement
Touch Reflexes: Chi Sao
Watch the Leading Elbow
Use Linear Striking Action
Avoid Fighting Force Against Force
Train to Use Two Arms at the Same Time
Uses Pressure Points to Make Striking Techniques More Effective
Uses the Same Meridian Pressure Points as Treatment of Sports Injuries
in every style of Wing Chun I have investigated I have never come across a style that endorses beating on the wooden dummy. Each style consistently emphasizes using the dummy NOT for conditioning, but rather, for use in learning the proper angles. In the case of this new interpretation or should I say modification of Wing Chun called Kai Sai Yim Wing Chun, (created in 1981) they break away from the principles laid out by Ip Man. Is this good or bad? Only time will tell.
The main thing is this....... this is not a good representation of Wing Chun in general. When a person asks a question about WING CHUN they should be given a WING CHUN answer. Pat.... in the future I would be up-front about the fact that you are training in a modern and modified version of Wing Chun. That way traditional practitioners won't think you're crazy.
now.... about Grandmaster Lo Man Kam.... the teacher of Kai Sai. They DO NOT teach to beat on the dummy. They are a traditional WING CHUN school teaching the traditional WING CHUN system that was handed down to him from Great Grandmaster Ip Man. Sifu Duncan Leung is Lo Man Kam's younger kung fu brother. Duncan Leung is also a person I myself have learned a GREAT DEAL from.... and never once during Wooden Dummy training did he ever once teach to hit the dummy hard.
But anyway, like I said before, good luck in your modern version of Wing Chun but remember......... without root, there is no tree. In other words, to better understand your modern system, it is best to trace it to its roots.