Due to discussions about bump map I wondered how look like 'real' spherical bumps on a sphere.
The following pictures show influence on highlights and shadows.of a different numbers of light sources.
Light sources are suns set to distance, with radius 1. Object's material is default matte. Tone map is the same fix brightness for all renders.
Brightness is adjusted to maximum for all pictures with less than 6 lights as the only post process action.
Locations of the six lights are top, bottom, middle 45° rotated front and back - left and right.
Did you guess highlights and shadows get this complexity? Okay there are six lights in the last scene and their hard highlights and shadows add from six positions. This sounds not exactly like a real case. Are you sure? What is with the number of fluorescent tubes in an average office. Or what is the number of spot lights in a bright shop?
The next picture shows influence of distant sun's radius on highlights and shadows.
As you may have observed bumps are best visible with small radius lights (like sun, point and spot lights) and hardly visible with large radius (like sphere, area and diffuse-indirect lights).
160.8 | 42.8 (10.7) Gfp / Windows 10 Pro, intel i7 4770K@3.5, 32 GB | AMD R9 290x+RX 5700 XT, 4/8 GB
17.3 | 19.0 ( 4.7) Gfp / macOS X 13.6, iMac 27'', 2010, intel i7 email@example.com, 24 GB | ATI Radeon HD 5750, 1 GB
#luxcorerender | Gfp = SFFT Gflops