I abandoned “Commute to and from Heck” because there were these weird black spots and freezes occurring during render. It turns out that if my model had overlapping edges, points, or some other flaw, the light hitting the model could exceed 1 (0 being complete darkness).
So imagine the frustration when a new problem cropped up. No matter what I tried, my textures were not looking right in brightness and color saturation, or (in the case of normals) they seemed not to apply at all.
It turns out that in passing my model back and forth between Substance Painter and Newtek Lightwave, the model itself had grown many times over and now measured approximately 720km long. Woah. So it’s interesting to note that Lightwave not only tries to keep the texture effects in proportion to the object, but it also has a limit to how high a texture can be made before the mesh falls apart.