I had a student recently ask me, “Now that I am on summer break, what should I practice to get better for next school year?” To answer that we should look at what practicing is and what it should not be. By definition, practicing is performing an activity or exercise/skill repeatedly/regularly in order to improve or to maintain one’s proficiency. That means we need to be working on a skill set regularly to improve that skill. Practicing should not be aimless. It should have a purpose and goal. That goal is to improve.
You have to look at your goals and figure out what needs maintenance and what needs to improve. I would suggest you practice your weaknesses. In terms of jazz improvisation-what are your weaknesses? Do you need to improve your ear training? If so, work on it. Do you need to improv your facility in the key of B? If so, work on it.
You have to take an honest assessment of what you need to improve in your playing. You become a more complete player when you consistently work on the parts of your playing that are not as strong as others. Write those goals down and put a realistic time limit on when you want to achieve them. Be competitive with yourself and you will find that you can rise to the occasion.
I hope for those of you that have a summer break/holiday that you take this time to practice your weaknesses and continually grow as a musician!