Why doess big band jazz generally play written music?

Big band jazz typically plays written music to ensure tight coordination among the larger ensemble, which can include multiple sections like brass, woodwinds, and rhythm. Written arrangements help maintain a cohesive sound and allow for complex harmonies and intricate arrangements that are characteristic of the genre. Additionally, having written parts enables musicians to focus on performance aspects, such as dynamics and phrasing, rather than improvisation, which can be more challenging in a larger group setting. This structured approach also facilitates easier rehearsals and performances.