In the shawl above X equals 4 while Y equals 9. It might seem that X is greater but there is a regular expansion of the lace band not only from within but also from the edge. I designed it to be greater than 180º and it is. It sits on my shoulders just fine.
In this 2nd case, X equals 12 while Y equals 3. This shawlette has 14 main points because of edge expansion. The shawl above has 10 main points. I suppose that the triangles would be less obtuse if X were greater.
Anyway one question I will ask my test knitters is what their X and Y are. I think I will want 3 standard sizes.