This might be apropos of nothing, but still interesting?
The white vectors are as before (“the unitized average of adjacent surface normals”), the black vectors (unitized) are obtained from the volume center point and each vertex. For 2 out of 22 vertices they are identical, where 5 faces meet on opposite sides of the polyhedron. For 20 out of 22 vertices they differ, though both look reasonable. All faces have the same area in this case.
brep_vertex_normals_2022Oct17b.gh (25.9 KB)