Except for that tiny minority of ambidextrous people, most human beings have a dexterous hand and a non-dexterous hand. We use our dexterous hand for things that require precision, like writing and the non-dexterous hand for holding and framing. I’m sure we’ve all tried to write with our non-dexterous hand before and found it almost impossible, but here’s another thing to try…
Put your non-dexterous hand behind your back and try to write as normal with your dexterous hand. You’ll find it’s hard because you use your non-dexterous hand more than you think, in this case, to steady the paper you’re writing on and stop it moving. Both hands are actually involved in writing, but both have different jobs. If you wanted to get all “Tai Chi” about it we could call it a Yin and Yang split between the hands, which work together as a whole, and talk about the sword hand, but layering a bit more philosophy on the concept is probably not necessary, I prefer the phrases dexterous and non-dexterous hands.
It’s the same in martial arts. I’m sure we’re all used to doing a technique quite competently on one side, then swapping it to the other side and feeling like a complete beginner. For this reason I’m quite against the idea that we should be able to do everything equally on both sides. Learning to do a technique on your non-dexterous side will be arduous, time-consuming and you’ll never be able to do it with the same flair, so why invest all that time in a pointless campaign?
If you look at the Tai Chi form (I’m thinking of Yang style, here since it’s the one I’m most familiar with) then you’ll see that some techniques are done equally on both side (brush knee, for example) but some techniques are only done on one side (all the grasp bird’s tails, for example go to the right, while all the single whips end to the left). I believe this is because the creators of these movements were well aware of the difference between our dexterous and non-dexterous hands.
In stand up arts of punching you see the same thing – people generally poke a jab with their non-dexterous hand to set up the big overhand from the dexterous side. I find if I put my dexterous side forward (southpaw) it results in a jab I can hit harder with but a cross that is less accurate.
But how do you choose which techniques to do on one side and which to do equally? The answer is simply to feel what works. And for this you’re going to need to do a lot of practice on another human, not solo form.
For example, in jiujitsu I have developed this one-sided approach through countless hours of practice. It’s most noticeable in my guard passing, but it also applies to my guard playing, although I’m not sure the idea extends to the legs – they both seem equally non-dexterous when compared to our arm! But in guard passing I notice that I naturally do some passes to my left and different passing to my right. For example, I knee cut with my right knee on both sides of the opponent’s body, so if I’m going left, I lead with my right knee and if I’m going to the right I also lead with my right knee – this naturally leads to two different techniques being used.
So, the answer is to feel, and don’t try to force yourself to do techniques that feel awkward because they are on the “wrong side” – look to see if there is something else you can do in that situation that fits better.