Why did Gustav Mahler revise Symphony No. 5 repeatedly after its premiere?

Gustav Mahler repeatedly revised his Symphony No. 5 following its 1904 premiere primarily because the initial performance did not go well, and the experience provided him with the opportunity to hear the work in its entirety and form his own critical opinions about it.1

The premiere in Cologne was challenging, and Mahler himself expressed concern about how the public would perceive the "chaos" and the "foaming, roaring, raging sea of sound" within the music. Recognizing that the work was spacious and complex, he felt that more rehearsal time might have improved the initial reception. Consequently, he continued to refine the symphony throughout the remainder of his life, conducting it nine more times over the next seven years and revising it anew before each performance, with the final revision occurring in 1911. This practice of frequent revision was consistent with Mahler's broader approach to his symphonic works, as he was a fastidious orchestrator who often adjusted his scores to achieve his desired musical goals.12