"WW2 IJN paint" Topic

I know the IJN essentially had 4 different basic grays based upon the yard that did the last work but was there a purpose other than simply what was available/used locally? Was there a tactical or some other purposeful reason Sasebo, Kure, Yokosuka and Maizuru greys were different?

None that I ever heard of. At combat ranges all these greys would have appeared exactly the same.

I once read an article about how the sequence of ships built at the various yards told you something about what certain poorly-documented features might have looked like – i.e. the yards to some extent repeated the previous design.

Eg Yokosuka built Hiryu then Shokaku then converted Ryuho then started work on an Unryu. I forget what specific features this was supposed to be informative about, but it wasn't the paint. It was an interesting way of looking at it.