Painting the same thing several times gives the artist a good look at all the details. Draw several sketches, then paint a small version. It sounds tedious, but I can tell you this is how I have created my best and favorite large works.
This is a 5 x 7 panel, executed quickly. The horse still dominates the scene, although his actual size on the canvas is about 2.5 “. Acrylic on panel, 5 x 7”