Dear Chris,
I'm with you on the unity of the painting. If for instance, I paint a lady with a blue dress, and the background has lovely oranges in it mostly, then I might add a very tiny pattern of the background orange color, such as tiny little textures into the dress to unify the dress to the background. Or, I might just, instead, paint some of the orange onto the blue dress in areas. And the blue from the dress would show up in the background somehow also.
If I were painting from life, then I would certainly co-ordinate the dress to the background before beginning the painting. That's what they do on movie sets and television shows.
But then again, I'm a big proponent, perhaps misguided, of unity and the dominance of one color and the dominance of temperature being very important also.
Also, when painting portraits on porcelain, then I paint from a full load of colors, but I also keep an additional portrait palette handy (my colors never dry until fired). When I paint portraits in oil, then it's the whole gamut. But Tim has a great idea here. I'll try it.
This painting is by Fritz Zuber-Buhler