I'm new to blender and digital modeling, and am trying to get a feel for the sweet spot for how many edges I need in a mesh. If my understanding is correct, I need edges only when defining a boundary between separate faces. I've attached a screenshot below (part of a simple sword mesh), in which I've highlighted a few edges that seem unnecessary. Is there any advantage to keeping these edges or can they simply be discarded?
It seems there's a disadvantage in that with excess edges, things like smoothing faces become unnecessarily complicated.