I ran across this some time ago and I'm going to respond according to my memory and reaction at the time. So, if I'm off a bit, don't stone me.
I read an article and watched a YT video or two with the guy who espouses this. He's an Indian fellow who also answered viewer questions. It seemed to me that it was more geared toward people who were balding or thinning and encouraged regrowth. Someone asked how long it takes and I think he said it takes, like, a year to start seeing progress. I pretty much tuned out after that. But, if you'd like to see this guy talking about the technique, it's definitely on youtube.
And, hey. It couldn't hurt to rub your fingernails together when you're not doing anything with your hands. But, I didn't think it was a serious growth solution. At least not for me.