I never saw Jerry look at his guitar neck. He was always looking straight ahead the dozen plus times I saw either the Dead or the Garcia band. My bands King Crab, Dwarf Rat, Lima Bean Wrist Rocket, The Huckleberries/Dead Country, have been playing the Dead catalog since 1975 when were in college. With a pedal steel player now, we really twist it sideways. Dark Star was my intro to playing Mixolydian. Plenty of songs are Major Pentatonic with Chromatic runs and doses of blue notes to connect phrases. One series of phrasing actually reminded me of a John McLaughlin’s ever changing riff patterns with Mahavishnu Orchestra.
Jerry was always searching for the sound, finding it more often than not.