During the paint wars where casualties were everywhere there was a running e-mail chain. I forget the exact abbreviations SMML?? John of S&S fame posted “ Your the Captain paint it what you want”. I fell from my seat and hit the floor. Made absolutely perfect logical sense.
For USN naval ships there was contradictory guidance and offerings. The S&S chips appeared one way, Mr Short’s mix guide appeared another, ColourCoats another, Floquil another and Testors yet another. All battling to be exact and correct for market share.
For me it eventually boiled down to which paint I liked working with and whose guidance would I trust. I tailored my stock of paints around that thinking. So I came home from the paint wars a lot poorer but more focused in what I wanted.
Some people like to know the truth, others just need to feel right all the time. Some embrace new evidence, others lash out at it.
Ground vehicles and aircraft are totally different in terms of painting practises, which further vary greatly by nationality and even chronology. 1941 Japanese aircraft painting practises were excellent. By 1945, they were terrible. British aircraft painting practises started off good and remained good. If anything the quality of paints improved.
There could be batch variance, but this is grossly overstated in the main, i.e. it's used as a ready made excuse for making errors. Industrial scale camouflage paint manufacture tended to be limited to a small number of pigments and generally lower cost ones more readily available. Some of the choices made by modellers and "justified" with the batch variance excuse would require substantial quantities of different, often rarer and much more expensive pigments to make. Sticking within the pigments actually supposed to be present, there's an envelope within which the resultant colour must land, and this determines the character of the colour. There's an exception to every rule - USAAF ANA613 Olive Drab. There is no record of any batch ever having been rejected. The US industry therefore may have the worst quality control of paints during WWII. Even Germany was getting significant deviations from their RLM standards due to pure absence of some pigments late in the war, but they at least recorded these facts.
The less one knows about how things are really done, the more these arguments make sense.
Paints weather. The same paint with the same binder and the same pigments tend to weather the same way. The rate may vary depending on the conditions, but a typical olive drab will never "fade" to a chrome green nor a bluish green.
Aircraft paint issues fall into three broad categories:
1) How they were painted at factory (this is well recorded in the main, for most nations)
2) How they were painted at Maintenance Units / Depots / whatever the specialist facilities most air forces used for this (this is less well recorded, but usually we know when serial numbers went in to them, and what the latest orders were in place at the time)
3) What was done in the field. There's much less of this than modellers like to think. The crappy camouflage seen on late war Japanese aircraft was field applied. Nose art and stuff like that kinda counts for the US forces.
Painting aboard US Carriers is somewhere between 2 and 3 above - there are examples of rough painting, but also examples of better painting with insignia stencil masks aboard ship.
I don't think aircraft or vehicle modellers are any more "anal" than ship modellers. There are plenty ship modellers who like to get things in the right ballpark too. It's fairly well accepted nowadays that many of the things believed to be true about Royal Navy WWII paints and camouflage were simply wrong and directly contradicted by primary source evidence that perhaps earlier researchers didn't have access to.
The wingnuts and tread heads are much more anal about color than ship modelers. The color standard was ANA but for the most part they were only suggestions. Different paint manufacturers produced colors to their own match. Factory paint on Monday differed from Wednesday. Heaven forbid you’re matching a field application. What was it thinned with; Varsol, gasoline, diesel, water?
Take your choice, go with one of the recognized paint brands; Mission, Vallejo, AK, etc. and enjoy it. Stay away from color chips printed in books. They are subject to printing variations.
Want to start a Pearl Harbor-type discussion? Go to an aircraft centric board and ask what color was on a P40 under the glass behind the cockpit.