It's not about drying speed, though increased surface area does speed drying, the surface area of a piece of clothing is too small to have a practical effect. From the practical standpoint, it's about how the cloth will be affected by it's position when drying. Cloth will take a "set" as it dries, which you will want to use to your advantage, and avoid an improper set. For example, hanging a shirt by pinning it's tail end will put the greater weight of the shirt at the bottom, which helps decrease (but not necessarily remove) wrinkles by using the weight to help draw the wrinkles out as it dries. Avoid folding in the middle and placing clothing over the line, as it will put a crease mark in it that can be difficult to iron out.

Drying time is much more affected by temperature and humidity levels of the area you live in than position on the line. When I lived in the Southwestern desert, during the summer, by the time I had hung the last of my clothes on the line, I could go back to the first item and remove it, as it had dried. Down here in humid Florida, that is not the case. A more extreme example is hanging wet clothes in the winter in northern climates. The clothes will still dry even though they will freeze first, but it will take much longer.