One topic that always comes up is what to practice after things wind down in December.
My personal answer when I was a student was to work on excerpts. I have addressed this more than one time in Horn Matters, with this article perhaps my most comprehensive on the topic. It is more directly addressed to summer breaks and horn students.
I have also suggested etudes, such as in this article. That is what I am practicing this year, mostly Gallay in transpositions (have you been working on your transpositions?). And of course if you have a recital or auditions coming you should have plenty to practice.
But over the years I realize that often I give or follow advice that sounds like bad advice but actually is not bad advice. So my holiday suggestion is to try mouthpieces over break.
With a side point being if you don’t own at least five mouthpieces you don’t own enough!
These both sound like rather bad advice but they are not. With the pressure of performing off a bit you have the space to reevaluate your equipment, would something else work better? No way to know but for actually trying something different.
In my own case, (UPDATED) after flirting seriously with the Houser San Francisco cup in brass, I find a bit more comfort on the Houghton H-1. (More on the reason why here). Testing mouthpieces does give you something to focus on, and that is really the key for your holiday practice, you have to have a project or something that gives practice some direction or focus.