There are two types of drum lines. One that anyone can join and you learn as you rehearse with the group. Most school band programs tend to be like this. Music is passed out, through trial and error students work on the music and by trial and error they learn the music and it comes together and a few months later there is a performance. Parents are happy with the result of the hard work. The missing element in most cases is teaching basic reading, coordination, rudiments, and reading technique. When students leave high school they usually lack in the areas most needed to survive in college groups or local bands.
Skilled performing groups, like typical Drum Corps, start with qualified players that are only admitted by passing an audition and the staff places members where they augment the ensemble. Members show up prepared. In most of these groups slacking off ends in loss of membership.
Let me help you, as I have with many students, become a member of a top Drum Corps International (DCI) Rated organization.