As for "many of us becom(ing) quite immune to the aspect of it", well that's just about the least scientific, most subjective statement you can make. After all, who is "us"? You and your buddies who have some how managed to develop super powers and inhuman pain tolerance, which eludes the rest of us? If you really can't feel pain from a properly applied nikkyo, you haven't developed a new skill, you've developed nerve damage. Besides, I betcha nickle I and several other members here can make it work.
Oh I'm SO SO SORRY that I didn't quantify and peer review my USELESS anecdatal evidence that I and many people no longer feel the electric jolt we used to. And I guess the term "lock" as in locking up the person's structure isn't what you mean by lock - I didn't realize "lock" meant pain compliance and I guess all the people on whom yonkyo doesn't work unless you actually lock up their structures, they just never felt a "real" lock either.
Fred, pass the popcorn.