US Naval Camouflage Paterns. I cannot imagine a more frustrating situation for a skipper in WWII than trying to keep up with all the Measures while fighting a war.
The Measures were around a year apart per each, and many were Theater-specific.
So, Measure 12 stayed "persistent" in much of the Atlantic, particularly the South Atlantic, where the major worry was being sighted from the surface (or by submarine periscope. With 11 the "go to" where aircraft might be present.
It was less effective in the deep dark sunny blue of the Pacific, and where aerial observation made Measure 21 the best choice. But, also Measure 22 where less aircraft were an issue.
The "splotchy" versions of 12 were more about martial appearance--and were very much to local command preference.
Ships spent a lot of time in port--it's the nature of the beast. Several hundred sailors consume a lot of consumables. So, you need to get to port. Fuel is not a casual item, either. SO, shihp deployments tended to be measured in weeks, not months or years. Most ship Histories for USN ships will show they were manking Port Calls around every 3 weeks or so.
Being at sea is hard on paint. So, there's constant painting duty for the Deck Department (which is often a hundred or more Saliors). And, with several hundred Saiors about, you can get paint on pretty quickly. Especially if you already have the paint handy.
This is why I have a huge gripe with those weathering USN vessels as if they had spent three years in Stalingrad. Or with the appearance of the average commercial vessel with a crew of perhaps 25. (Subs get a "pass" as they were very beat up on patrol, and painting them was not a huge crew priority.)
Now, being a Port Captain, and having to maintain the raw paint supplies to equip every visiting ship--that would be thousands of 5 gallon and larger buckets of paint. Flammable paint that is sensitive to storage conditions. And if you were not near a rail connection for that supply, you had to wait for a supply ship filled with paint buckets & barrels.
This is why ship modeling is so requisite on photos, too.
Consider USS Texas. She was in Measure 12 in 1941. Then Measure 12 (mod) for 1942. Then, she wore Measure 22 for '43 and '44, to end up in Measure 21 in 1945.