Refrain from asking your college professors "Do I have to do this?"
My answer will always be, "You do not have to do anything but die, for even paying taxes is optional and you can always choose jail."
Often times students refuse to complete an assignment unless the professor specifically requires it. In essence, if the instructor fails to designate a grade to an assignment, then students feel no need to complete it. Teachers do not assign activities or homework to torture students and keep them busy. Practice activities provide needed review and serve as support for everything else a student does in the class.
So if you are wondering if you "have to" practice, then again my answer would be, "there are no "have to's" only "want to's." Avoid a negative attitude toward an assignment or a course in general. When you pose such questions directly to the professor, you send out a negative vibe that may not actually reflect your true feelings or desires.
Try radiating enthusiasm and interest for the subject; show eagerness to learn, practice, interact and explore new ideas. As long as your teacher respects your basic Constitutional Rights, there is no reason to be combative or negative. After all, college is like training camp for athletes. You can practice, make mistakes, learn, adapt, improve, fail or excel. In the end you make the top of the list or you are eliminated from the team.
You ultimately decide what you do or do not have to do. You decide your path, your own victories and your own defeats.