NURBs surfaces and curves are not defined by vertices. A curve is defined by a polynomial function where the degree defines the smoothness and inflections within the curve. Think f(x) -> x is a straight line and has degree 1, f(x) -> x^3 is a cubic curve and has degree 3.
Maya supports nurbs curves of degree 1, 3, 5, and 7. However, degree 5 and 7 curves are rarely if ever used in maya. They are there mainly to support import of nurbs data from more sophisticated nurbs modeling apps.
If you search "nurb" and "continuity" and my nick "ctbram" you'll find a couple posts I have made that attempt to explain surface continuity and a bit more about nurbs surfaces.
So with all that being said if you want a 2-vert per edge model then you will want to be working in polygons and not nurbs.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 15-11-2012 at 09:35 AM.