Yes, the artists were handpicked at the time this process started, and a lot of credit also goes to the project coordinators, Ben Tolman and later Joe MacGown, who joined the panels and made the transitions, often adding the shading to blend the work into a cohesive one. Usually we were given the adjoining panels to work with, so we sort of matched it also ourselves.
I am happy about and thankful for the @curie vote - it made the effort to put this post together worthwhile. Also the video: I produced it at the same time with this post in mind!