Have you ever had to retake a major course you already passed in order to understand the subject better?

So essentially I took a class last semester, passed it, but didn’t learn shit because I rarely attended the lectures (worked evenings, class was in AM, used the hour to catch up on sleep). I didn’t realize how important the class was to my major, and now I’m seriously struggling in my current classes.

Have you ever had to retake a prerequisite in order to better understand a subject?