seriously?? I didnt know such a thing existed, not until I came across this video:
"Narciso Yepes was one of the first classical players to utilize this technique to play speedy scales with ease. The flamenco player Victor Monge Serranito also uses the 3-finger picado technique quite effectively.
This is an introductory exercise. Always use the rest stroke (apoyando).
Again, ramp up the speed very slowly. I did the whole thing in 3 minutes for demo purposes. Start at a much slower tempo and build up slowly."