Of course, you could do everything with Grumbacher Red, Ultramarine Blue, and Cadmium Yellow Light and White. The colors I used are convenience colors. It's easier to know Cadmium Yellow Light and/ or Alizarin Crimson with Naples Yellow and White can be conveniently used to approximate the hues you might be looking for. In shadow you might cool it with a green or blue, or a Cobalt Violet that already has a blue component to it, and that you already discovered worked well with that Cadmium Yellow, for example, again demonstrating the convenience a palett evolved through your own experiences can impart.