Placing the information here for others interested in this thread not that you need this information tomanydemons.
I do not think EMI was saying that you created a hard edge smoothing group but a 90 edge is consider a hard edge. Now it is not a real hard edge smoothing group and will not be treated as a real hard edge smoothing group. The term hard edge can cause some confusion.
My workflow. I would bevel a low-polygon box. Yes it adds a little more geo but removes any shading issues as you soften the transition between the normals. This is what I was talking about. I also model to reduce the wavey normal map areas that can appear in a low polygon model.
With today's games engines and powerful computers plus mobile devices, the vertex count in the low polygon model can be greater. This would include the added uv set vertices. This does not mean you go hog wild.
I include 3 pictures.
1. Left cube with just the 90 degree normals. (hard edge), Middle cube (bevel), Third cube. All edges set to a smoothing group with hard edges. The first picture in Wings3D has smooth shading turned on.
Left cube has shading problems.
Middle beveled cube much better.
Third cube, set all edges to a hard edge smoothing group. I am just showing here for others interested in the thread. Normally depending upon the model you will have some soft and hard edge smoothing groups.
Second picture. Shown in flat shade. Orange edges show on 3rd cube I have set the edges to a hard edge smoothing group.
3rd pictures shows normals.
For those interested, a couple of links