One of the main requirements to be a successful landscape photographer is to shoot during the golden hours, either at sunrise and sunset. In fact, many magazines will not even consider photos that were taken during other times, no matter how good they are.
Even when not publishing, there are certain places that the only way to get a good picture is to shoot during the golden hours. The Grand Canyon is one of those places. Photos shot during those times add depth and definition to the beauty of the canyon. Any other time, photographs are flat with little or no definition because the sun is higher in the sky thus casting very shallow shadows. This shot from Yavapai Point was taken just before sunset.