I just stumbled across an article about a number of topics I was interested in for product photography, especially how surface reflections behave in different lighting and with different light modifiers and distance from the subject.
So instead of rehashing it here, I link to the source below.
Thanks, John Cornicello, for making that resource available for all of us!
John explains in his article a number of important concepts when trying to light subjects in a studio environment. Surface reflections, diffusion light modifiers, distance of the light source from the subject, these things.