Stirring the smooth sands of monotony is what changes the musical landscape from common to uncommon [ See blog, Monotony ].
Whether you're composing or improvising or performing repertoire, your listeners will take more interest in and notice more of the countryside when your music takes a turn down Unexpected Road.
Composers at times have been able to make this turn by imposing certain restrictions upon themselves [See blog, A Place On A Pedestal].
At other times it's because they took liberties that probably would not have been allowed in the composition classes of certain college/conservatories of music and major universities where classroom fugues and the rule book reign supreme at all times.
It takes courage to depart from the well worn grooves of the ordinary and risk the ire of the critics, but it's essential to the progress of art.
The gutsy double Fugue from Prelude and Fugue in c minor Op. 11 is an example of this [See blog, Getting Started With Writing, Part VI].
When you're writing your own music, improvising, or performing repertoire, don't kill your audience with surprises ... but surprise them a little bit.
Do something unexpected in every piece.