3D

If you find you are unable to move a curve handle in all three axis, it is probably due to the curve type being set to 2D. When you create the curve expand the Simple Curve dialog in the lower left of the viewport, or press F9: From here choose 3D and then, if you want curved splines, choose Auto in the Output Curve Type. The defaults are 2D and Vector and they may not be what you want for your curves....

In recent years, there have been huge improvements in n-gon’s (non quad polygons). Specifically how well they render and games engines handle non triangular or quad polygons – in reality of course, all polygons are reduced to triangles for rendering. Three vertices being the lowest amount of points that are needed to create two dimensional forms. It seems now that the last place that require quad sub-D models is in deformed meshes, character animations and the like....