Django and his shadow

This is my friend Django, an excellent guitar player, who graciously allowed me to practice on him. For a while now I've been running away from deep shadows. But if we never try, we can never figure it out, right? So now I'm trying. Here's the question I played /will be playing around with: How solid should the deep shadow be? If it becomes too deep does it render the person flat? How much shadow is too much? But if it's shadowed like I did on Django's face and neck, does it appear too "raggedy" for lack of a better word? OR if I did it solid, as in one solid line denoting the edge, would THAT make it appear weird? This begs further exploration. :-)