Iāll start with generalities and Iāve on to some specific observations regarding WC.
First, you need some foundation of techniques and principles which can work in a fight, WC has those.
Next, you need to give the students opportunities to apply those techniques and principles under pressure with the possibility of failure included so that the student can learn from the results. It doesnāt mean that you have to jump right in to full MMA style sparring against practitioners of different styles, but there should be a progression leading that direction.
In the beginning itās good to give students isolated moments that might come up in a fight and give them a task to accomplish in that moment while their training partner tries to prevent it. For example when I teach students how to perform a single leg takedown I might give them a drill where one student having already scooped up and captured their partnerās leg. Then on āgoā, the first student tries to complete the takedown while the other tries to stop the takedown and free their leg. Iāll watch the students work this drill for a few rounds, observing where the problems are. Then weāll take a little break, discuss the difficulties students are having, Iāll point out some specific technical flaws that I saw getting in the way, then Iāll send them out to try again and see whether the success rate goes up.
Getting to WC now. I spent some time a few years back training Wing Tsun with
@yak sao. I learned some cool stuff, some of which Iāve been able to use on occasion in MMA sparring against reasonably high level sparring partners. Yak sao himself I am confident can use his WC skills effectively in a fight. However there are certain aspects of how he and his lead assistant instructor were teaching at that time which I think were counterproductive for helping his students learn to fight effectively.
(I spoke privately with yak sao before writing this post to get his approval on posting this feedback publicly and to make sure this doesn't come across as disrespectful or an attack, because it's not meant to be either.)
At the time* yak sao was teaching primarily forms, footwork, specific technical applications, and some assorted non-pressure drills. There was no sparring and it was rare to see even beginning level pressure testing. His idea was that if the student doesn't get the WC body mechanics and structures fully ingrained before sparring, then their technique will just fall apart into sloppy, crappy kickboxing once they are put into the stress of sparring.
*(I haven't been out to see him in a while, but he has mentioned that he is doing some things differently now.)
I understand this idea, but in my experience this will happen regardless the first time a student is thrown into to the stress of free-form pressure testing scenarios such as sparring, regardless of how long you give them to ingrain their form through preset drills. Beginning BJJ and boxing students have terrible technique and form when they start sparring. Their technique gradually improves because they discover the correct body mechanics reliably produce better results under stress. In addition, they become desensitized to the adrenaline rush and they encounter instructors and senior sparring partners who can reliably dominate them in sparring through the application of correct technique. Personally I would take no longer than 6 months to introduce new students to the fundamental technical repertoire of the style before starting them out with sparring. More limited forms of somewhat free-form pressure testing can start earlier.
At the time I trained with yak sao's group, I was regularly taking what I learned back to my home gym and testing it out in sparring. I was the most junior (in terms of WC) student, but I didn't see the senior students with years of training doing anything similar.
In addition, the option of learning from failure seemed to be generally lacking even in the non-pressure training. I'll give an example from a class I attended which was taught by the senior assistant instructor. We were drilling an approach for dealing with a boxing style jab. The idea was to smother the opponent's technique with a pak sao, aggressive footwork, and a flurry of punches. This can be a valid tactic under the right circumstances, with the right timing. I was having no problem with the drill, perhaps because I have plenty of experience in dealing with boxer's punches. My partner, however, was struggling. I was doing my best to be a good partner and make it easy on him. I was feeding very slow jabs, with no feints, and no footwork. However I was using good boxing form and returning to a proper defensive guard as my jab retracted. My partner was hesitating on his reaction and so by the time his counter attack arrived I was already covered against his punches. His form was adequate, but his timing made the technique ineffective. The assistant instructor came over and watched the proceedings. His solution ended up being telling me to stop recovering to the proper defensive guard and just drop my hands after my opponent's pak sao so that he could get the experience of throwing his ending flurry of punches towards my unprotected face.
Needless to say, I consider this to have been absolutely useless and counterproductive for my training partner's progression towards being able to fight. He was already drilling the basic movement and body mechanics, so forcing me to feed him bad technique didn't help with that part of the process. The next step was to understand the basics of the timing and without being able to see my recovery he would have no way of knowing when he got that right. Without learning that basic timing, he would have no way to further progress into understanding the more advanced aspects necessary to make the tactic work, i.e. dealing with the opponent's footwork, dealing with the opponent's feints, understanding the moments in a fight when the tactic might work and when it definitely will not, dealing with the opponent's counters to the counter, and then being able to put that all into play under the stress of someone actually trying to hit him.
The frustrating thing is that I'm quite sure the assistant instructor knew what my partner was doing wrong in terms of timing and what needed to be fixed (at least for that level of the drill). He just wanted the student to experience the technique as "winning" rather than let him experience the "failure" of not being able to know that his punches would have landed.
In my opinion, you have to (as drop bear often puts it) "invest in failure." Let the students experience how their techniques can fail even with minimal resistance and help them fix the flaw which cause that failure. Then let them experience how they can fail with mild resistance and help them fix those flaws. Then gradually up the difficulty until they can function at least in full-free form sparring, preferably with some solid contact and preferably with time spent sparring against people who are proficient in other systems.
Speaking of sparring against practitioners of other styles, it's a good idea to become familiar with at least the basics of how those systems operate rather than making assumptions and trying to teach counters based on uneducated assumptions.
I have to give yak sao credit for this. When we started getting together, it was to trade information and training. After a while, due to some personal things going on in his life, he realized that he didn't have the mental energy to actively study another system at that time but invited me to continue attending his classes for free because he thought my training background would be helpful for the other students. He also encouraged his students to train with me when they had the opportunity, although only one took him up on that suggestion.
His assistant instructor (who was running most of the classes for a time) I don't think placed that same value on my experience. I've noted the incident above. I remember another time when he was showing how to pressure blitz a boxer and I showed how my natural reaction in that situation would be to shoulder roll the chain punches, pivot out, and counter with a left hook. He had an idea about how he would deal with that response, but while explaining it mentioned that the hook wouldn't be too powerful from that position. Yak sao was there for that class and commented "Tony did just say that was one of the most powerful punches in boxing." He was paying attention. His assistant was not.
(I also had some discussions with one or two of the other senior students which revealed a certain dogmatism and misplaced certainty that their system contained all the answers.)
Bottom line: Do your forms if you want. Do your isolated drills if you want. Certainly drill your basic techniques and applications without resistance in order to learn the body mechanics. But you have to spend time regularly pressure testing your technique with non-cooperative training partners or it's just not going to work reliably. (To be fair, there's also the option of just going out and getting into a whole bunch of real fights. However this is generally inadvisable from a legal and medical perspective. Not to mention that due to the non-progressive nature of the approach will make it hard to achieve mastery of the more subtle of difficult techniques.)