Glenn was a GREAT picker along with Jerry Reed, Roy Clark, Tommy Emmanuel, Les Paul, Chet Atkins......look up any of these guys and check out their skills also. They are all spot on with their techniques that some probably took years to hone (think "sweeping"). I could spend hours on the internet just watching videos of them alone or with each other. Amazing talents. One example:
https://www.youtube.com/watch?v=Pz2hXI7Ny9I