There is no shortage of different colour theories. These theories have been developed for or are used by various technologies. For example house paint manufacturers tend to use the Munsell theory of colour. Every artist paint manufacturer and instructor seems to have their own pet theory that will help artists. For the most part I’ve found these theories to be confusing; mostly because they don’t add much that is useful for the artist. These systems of colour differentiation provide the ability to do accurate calculation as to the exact colour represented. If the goal is to build a machine that provides accurate colour matching of a manufacturers paint colour then these systems are great. If your goal is to mix some paint to match the fall colours of Poplar trees then I would toss all the theories out and go back to kindergarten.
In kindergarten I learned that blue + yellow make green, red + yellow make orange and red + blue make purple. Now if I take any one of these mixed pairs and add a little of the third colour I get a brown that various colour theories call secondary, tertiary or sometimes complementary (and a host of other names). I think it’s brown. Various shades of brown but brown. It should theoretically be black but paint isn’t a very efficient colour agent so I need some black paint. I need white paint to make light colours, some colour theories call them tints. There is also additive and subtractive colour theories. Additive theories are used with computer monitors and Web design but if I’m painting a picture then I go back to kindergarten.
So I have blue, red, yellow, white and black paint. I can mix all, or at least most of, the colours. I can mix all the colours but some of them don’t look so great. I think that’s why there are so many paint colours. I use Dioxazine Purple because it’s a really nice purple that is difficult to get with just red and blue. Kindergarten really taught me everything I need to know to paint. Maybe to be an artist I need to know a few details but I worked them out or learned them over time. 50 years on I now have 17 paint colours in my paint box but I only use five of them consistently.