You're production oriented, if I read between the lines correctly, and you make common, valid, generally accepted approximations because of that. Most of the rest of us in this forum are interested in some of the higher order approximations, and a definitive statement such as, "andhedral has little no effect on lateral stability", is bound to bring counter-argument. If that's so, why bother with dihedral? Why not just make all wings flat and avoid all the bother of the structural difficulties with dihedral? Designers of model aerobatic airplanes go to great lengths to find the correct dihedral angle that results in as little roll coupling with yaw as possible. Even a small amount of coupling is annoying to an aerobatic competitor. And of course most trainers have positive dihedral because it's important to the handling qualities for a trainer. I know that yaw-roll coupling is not the same thing as lateral stability but it's related. Airplanes with neutral yaw-roll coupling are neutrally stable in roll, and so forth.