@rottendoubt--you are seeing the correct order of steps. Painters add paint layers, especially when working in oils, to give depth to a work. The underpainting (those layers that get covered up) do show through in a very subtle way. It is a very old technique that goes back to the first use of oil paints in the 16th century in Italy. That is one of the reasons that oil paints are still a preferred medium for painters, the subtlety it lends to color that you do not get with a more opaque paint.
