Thanks for sharing. This is a well-written and well-presented account of how mass-produced woodprint paintings show noticeable change between early- and later-printings.
That's a really great article that brings some solid facts to the question. That guy did his research.
They kept running editions off the original wood plates but the plates slowly wear and because of that colors changed from edition to edition. My father bought a 3rd edition print in the 60's when he was in the navy stationed in Japan. It's a bit muted, especially in the sky compared to the first runs I have seen in museums.