I wanted to do an  abstract painting that has all the colors of the color wheel. I kept them all at about 50% intensity which  gives harmony to the painting while allowing a variety of values for contrast. .I did not use a grid for my patches of color but painted the squares on randomly.  This approach ended up with my having to fill in areas that were not squares but
rectangles.  When finished, the painting has a feeling of a movement on the surface as if the whole arrangement were going to break up.