What is the benefit of using both red-orange and yellow-orange in a sunset?

Correct answer: It creates gradual warm transitions and depth

The governing concept is a related warm-colour transition. Red-orange and yellow-orange are neighbouring tertiary colours on the warm side of the colour wheel, so placing or blending them together can create a gradual movement from red toward yellow. That controlled change gives a sunset more natural variation, visual richness and depth. They do not create coolness or monochromatic grey, and using both does not automatically remove complementary contrast elsewhere in the painting.