He may have learned it from other gypsy players, of whom two of his chief influences were banjoist Gusti Mahla and guitarist Jean "Poulette" Castro.
[3] However, this technique was commonly taught in numerous guitar methods in the early twentieth century and was employed by American jazz banjo players.
[2] Many players have found a way to incorporate legato in the middle of picked passages, either with strictly alternate strokes or with sweeps.
Notable players who have used legato together with picked notes to achieve higher speed and a more smooth sound are Eddie Van Halen, Paul Gilbert, Buckethead, among others.
Author Chris Brooks refers to this as Compound Picking and used it as the basis for the 2017 book, "Neoclassical Speed Strategies".