Sacred Haven of Debauchery

That’s exactly what Reven was talking about in his thread, and I have the same experience. On one layer, I’ve already applied the full paint job, with highlights, shadows, and everything else. On the other, I’ve just filled it with a flat color. In general, the layer with the shadows does most of the work; the other layers just complement the overall picture, and the shadows determine a large part of the volume and effect.