So, it is a dilemma. The solution, of course, is to
do it in an organized manner as seldom as possible. In "live performances"
the interaction of the band with the audience often leads to displays of
peaking emotions and on this happy occasion the shake can be very effective.
It is my theory that the shake, like most ornaments
of jazz, was originally un-planned, perhaps a mistake, but had some quality
of excitement about it that led to imitation. The first shake that I ever
heard was done by Louis Armstrong who had a strong emotional vibrato. He
was playing the final chorus of "When You're Smiling", a simple thrilling
rendition of the melody in the upper register.
Because of the closeness of the harmonic series above
the staff, a tone apart, and because of the intensity of his vibrato, he
went into a brief shake on some of the notes and in my opinion, that is where
the shake was born.There may have been earlier examples that I don't know
of; it doesn't matter, that is where I learned it and it wasn't until then
that I heard anyone else do it. I heard a great many after that and played
a great many myself. Louis often lapsed into shakes particulary in his later
career but I believe that he rarely did them deliberately, and of course,
that is the best way to do them.