Well, when practicing music you shouldn't play a song more than five times, otherwise your brain goes weird and you're not really practicing.
But since Christmas is on its way I have to start practicing my Christmas music. So now I have Etudes, Hanon, Boureè (or however you spell it, it's french), Alla Turca, Do You Hear What I Hear, and the accompaniment for O Little Town of Bethlehem.
For clarinet, I have all my band music, which consists of The Magnificent Seven, Exaltation, How to Train Your Dragon, Russian Christmas, and Lexington March. I also have to do that one piece, I can't remember what it's called, which takes about ten minutes to play, and whatever I have in my Rubank book.