A much misunderstood feature of every sonata collection is the Table of Contents. Looking at Vol. I of the Mozart Piano Sonatas we see the following order of keys: C F B-flat E-flat G D. Six sonatas, written one after the other. Is it a progression?

Or take the first three sonatas by Beethoven: F minor A major C. Also a progression, but a less obvious one: 1. Four flats; 2. three sharps (its inverse);
3. Look, Ma! no sharps or flats!

If ever there needed to be an argument in favor of the black key / white key fascination of the piano when it was an innovation I propose these as evidence.