I'm a visual guy... Just a comparison. The shadow over this forehead (attached) is a DM spot, using shadowcam and Angle start/end. This would be nice to cast a few soft shadows (under #29 chin, ex). The shadows(attached) that are casting the darkest are RayTrace 1.000. The only good being the shadow under her eyelid. If you like outdoor lights, I think your "sun" should be a depthmap spot/with shadowcam zoomed. Maybe bias at 0.650. At least for a closeup. The fill would be globals. Keep one RayTrace (global) for reflects, but depowered (0.4-0.00001) A RayTrace global "sun" might work for a large scene. So many compromises, it's hard to say without having identical tests.