What is the most convoluted standard musical form?

Question

In musical composition, we tend to reuse sections of a piece in patterns that are referred to as "musical forms". Some basic examples of these that I know of are ABA, AABA, ABAB, and the rondo form ABACAB'A. While I recently became interested in finding out about more varying musical forms, the only one I was able to find that somewhat matches what I'm looking for is the Sonata Rondo form's infinitely varying ABACADAEA... pattern. With that said, are there any musical forms that meet both of these requirements and contain more variations than the Rondo form?

Answer 1

I'm thinking of program music (that tells a story), fantasias, and extended sonata forms. The most complex examples of the latter are certain longer movements from Mahler and Bruckner symphonies.

Answer 2

12 tone.