I agree the settings seem to be a bit all over the place.
It depends on whether you are viewing with the internal Engine or OpenGL and then also on the material (surface) settings as well (reflection, emission, glowing, etc.).
Also on you rotation and the location of the sun.
I use Sunlight 50%, Contribution to ambient 30%, and ambient at 40% - maybe it is just a touch on the bright side but seems pretty good for most of my materials.
You could also turn the sun off and turn the ambient up and you will find you don't get the light and dark sides.
The stronger you sun is the more effect it will have.
Think of it as a bright spotlight that will over expose a surface if it is shining on it.
The ambient light is more like the light in a well lit office - comes from all directions with no one particular source.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11