I am faced with the choice of what to do with situations where light hits a surface at an obtuse angle, which of course doesn't happen in real life but occurs frequently with low poly meshes. The amount of diffuse reflection is of course zero, but what do I do with glossy reflections? Should I just allow the light to bend "backwards" as if the normal was pointing the other way, or force it to zero (which produces clearly visible jagged edges)? Or something else, maybe some kind of soft cut-off beyond 90 degrees? What is more common?

(Edit: It just occurred to me that this was probably a silly question. The pixel would of course be in the shadow just as much with an accurate high poly mesh that it would on the low poly mesh. So, forcing it to zero is probably the correct choice.)