Multi-span surfaces are used mostly for quick or concept modeling, where the requirement to create the geometry quickly outweighs the need for surface quality.
The quality limitations of multi-span curves and surfaces are at the segment boundaries between spans, shown by isoparms on a surface and edit points on a curve. In these two examples of a degree 3 curve, the first is a single-span curve and has edit points only at each end. The curvature plot is smooth.
The second curve has interior edit points. The internal continuity across these edit points is G2 (curvature), which is fine for general CAD modeling, but may not be good enough for Class A surfacing. The curvature plot clearly shows G3 breaks at the edit point locations. The problem is less exaggerated for higher degree curves and surfaces, and more noticeable for degree 2 geometry.
The Pick
Component tool has options that let you select only single-span or only multi-span surfaces.
The Surface EditNURBS to Bezier tool converts multi-span surfaces into groups of single-span (Bézier) surfaces.