Some aspects of the strip became repetitive, but visually they became stronger, especially in the sunday strips after he got free hands to break up the frames.

Some aspects of the strip became repetitive, but visually they became stronger, especially in the sunday strips after he got free hands to break up the frames. So I suspect he realized he had reached the limits of the newspaper strip medium. Going further would require changing medium to something like comic book format. He did produce some childrens book formats.