If Roy Stevens & William Costello are the holy grail to playing then why isn't everyone doing it?

Roy Stevens - Over Again

Roy Stevens and His Orchestra - I'm Coming Home - Rollin' Stone - 78 rpm - King 15126

Trumpet Lessons no pressure high note Roy Stevens/Costello System Palm Exercise

Tribute to Roy Stevens of the 29th infantry division

The Story of Bedford Boys Ray and Roy Stevens (Part I)

The Story of Ray and Roy Stevens on D Day (Part II)