Hi, @M-777! I don’t have a ton of first-hand experience when it comes to modeling to a specification, but what I’ve read and experienced throughout my journey with CG gives me two pieces of advice/principles.
First, find out the requirements and work toward satisfying those. Your approach will be different if you are modeling for a video game asset versus a feature film.
Second, everything in CG is a cheat. You can hide some less-than-perfect work if the shot has lots of motion blur, the scene is dark, or the item is obstructed.
I guess that boils down to asking what the requirements are and walking the line of what you can get away with without negatively affecting image quality or render time.
Hope that helps!