In Jeet Kune Do we believe in your dominate side forward. This is usually you hand that you right with or throw a ball with. We tend to be more coordinated on this side. It's also our more powerful side. Most Jeet Kune Do schools will teach the right lead. Generally the majority of the students tends to be right handed. For the sake of making things simple for the class, some instructors insist that left handed students actually train out of their right lead. This is sometimes done because some drills work better out of being in the same lead vs. mixed leads. Although eventually you want to train that everything doesn't matter what lead you are in or they.
So one thing I do advise is training out of both leads. And here is where the question was asked. A new student of mine who trained in years of Wing Chun had a different thought process than my own. Some instructors shy away from teaching any other lead besides the power lead.
Here has been my thought process and what I have always used in my own teaching. I teach both leads. Initially I teach and have the person train their dominate side first. Even if that happens to be their left lead. It makes life for the student easier and of course it makes my process of teaching a little more difficult but I am there not to make my life easy. I am there to make the student learn the fastest that they can. So no matter what the students lead, I have them train their skills out of that lead. Why?? Many movements or basic tools you can watch someone do and see what they are doing but it's hard to replicate. And you are also looking to get a certain feeling for it. That sensation where you felt exactly what you have been trying over and over to get. Once you feel it, you quickly can start to replicate it. And when it's replicated you also know cause you recognize what it feels like when it's done correctly. The more you keep training it and getting that correct feeling when done properly the quicker it becomes natural and muscle memory. Now that we have a good feeling what it should be like on our dominate side, we can switch to our non dominate side and work. We already know what it feels like when done correctly. So we are spending less time searching for what it feels like. Even if the student can not achieve on their non dominate side they can switch back to their dominate side for a moment to feel what it's like when done correctly and find what they are missing on the non dominate side.
So.... What produces faster results. Lets make up some numbers on a new kick never done before. Lets say on the dominate side it would take 1000 kicks if never done on either side to get a good feel for the kick. But if they started on the non dominate side it would take 2000. Well a couple things here that has happened. One... they have to kick a lot more to get that good feel for the kick. I am using 1000/2000 but the numbers may be an extreme amount more or less. That extra amount to grasp what they are seeking is wasted time that could be used more productively. Plus the person may actually become frustrated and abandon the effort. So this is the reasons why I promote my students to train the dominate side first. It will come faster and usually easier. Then work your other side.
Once you have a grasp for the new skill well then I think you should train that new skill on both sides. Most people will always be better on their dominate side with a skill. Even if you train your non dominate side even more. It just seems like we are geared to having a dominate side. We even tend to have a dominate eye. Ask someone to look through an empty roll of paper towels like a telescope. Without thinking they will use their dominate eye.
Training both leads should be an obvious reason. We are not always going to be able to use our dominate side in a self defense situation. We may have injuries, or may even be injured in the fight and have to switch. Additionally attacks will not always come from your dominate side. And you don't have time to switch leads. It was a training injury that really made me train a lot out of my non dominate lead and hence made me really good in both leads.