Volumetric vs Contrast Paint

I'm new to the hobby and been researching painting methods such as volumetric and using contrast paints. From what I understand, volumetric is basically choosing an imaginary light source and painting it by using gradients of color that go from light to darker for light and shadow. On the other hand, there appears to be a method of creating a shadow effect by using contrast paints that pool into gaps to give the impression of shadows and light areas.

To me, contrast paints seem to be a shortcut method of just creating an impression of light and shadow that gets the job done quick, but not as accurate as one could do with volumetric painting. Is this correct, or am I missing something?