It is not so much the shadows being cast as the amount of sun and ambient light and the % of sun included in the ambient light as Erich mentioned.
Also the material (or I should now say Surface) settings will have an impact.
For example here is the same material but with different Reflection > Ambient settings.
Other settings in the materials may also have an effect as well.
Barry.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10