Tight value and color can be a boon to making large art. Pre-mixing paint based on studies, or an underpainting allows an artist creative freedom to intermix any color.
Color mixes use value, color and harmony. Sky and Cloud focus. (Beach, Dunes and Water is next).
When planning your project allow for plent of time to mix puddles of color. Mix all 3 primary colors for the best harmony, especially as works get larger.