/ic/ - Artwork/Critique

Where does saturation go? does it change from material to material? I know that you can use saturation to make a particular object or thing pop out in your painting but how do i understand how saturation occurs in real life? Is there any somewhat clear answer to that? I know that generally speaking when an object is lit the most saturated part of it is the halftone but at the same time i know of paintings that break this rule where either the highlight or the shadow is the most saturated thing. Like in this pinup Look at how red and vibrant the shadow is. Whats up with that?