There are multiple reasons for "directionality" in various cable designs.
The first and most obvious reason would be due to a specific type of shielded design. Many cables make use of a shield that is grounded at one end and floating at the other. Some refer to this as a "drain wire", "telescoping ground", etc... This type of arrangement can be used facing in either direction, but in most cases, the shield is tied to the "source" end of the components. If one were lifting the grounds on all of the components ( in order to avoid ground loops ) except for one ( such as the preamp ), one could argue that the "grounded" end of such an interconnect should be connected to the component that is grounded. Otherwise, the benefits of the "drain wire" are pretty much minimized.
The other type of "wire directionality" has to do with how the wires were formed and / or drawn. Logic would dictate that the wires would be "pulled" in one direction, resulting in a specific pattern within and on the metal conductors themselves. As such, the flow of electrons "might" have an "easier path" going in one direction than the other. In order to achieve the best results if one were to take such things into consideration, the "hot" wire should flow in one direction and the identical "return" or "ground" wire should be configured in the opposite direction. In effect, the wire would make a big "U" electrically without it ever changing the direction of flow or way that it was drawn within the cable itself.
The second example takes into consideration that conductors have a crystal structure that is formed within the wire itself and said crystal structure not only affects the flow of electrons, but are also audible within the confines of a hi-end audio system. Should one choose to believe such things, one direction of flow "should" be superior to the other IF both wires were oriented "correctly". If that is the case and the cables used identical conductors for both the hot and ground with no external shielding, you should be able to turn the cables around and notice a difference. If you don't notice a difference, it is possible that the original geometry and design of the cable did NOT take the original "draw" or directionality of the conductors into account and may be reversed ( actually "non-inverted" ) within the pre-made cables themselves. Since most pre-manufactured cables use totally different conductors for the hot and ground, i don't think that many of them pay attention to such things.
In a design that does use identical hot and ground conductors and attention to signal flow was not paid attention to, rather than a "U" where the signal can start at one end travel to the other side and return to the point of origin without running into any type of lack of continuity or "break in the flow" of the crystal structure, you now have two "I's" standing side by side ( I I ). As you can see, the paths are identical yet there is a break between them. That break simulates the change in direction or "lack of continuity" in crystal structure that the signal encompasses when trying to complete one full cycle. Both cables are of identical design and face the same direction, but the connection between them does not "flow" the same as a series of electrons ( or music signals ) would. In such a case, the electrons would have an "easy" path going one way and a "harder" path, flowing against the grain or "crystal structure" of the wire. This would take place no matter how many times you swapped cable ends from component to component as the problem is within the cable itself.
I think that this is part of what takes some cables MUCH longer to "burn in" or "settle" as compared to others. The electrons are literally having to "fight" the crystal structure that was already present before things can fall into place. Obviously, more broken or jagged the crystal structure is along the path, the longer it will take to smooth things out. That is why many manufacturers try to use "long grain" copper, etc... as there is less potential for "breaks" or "jagged edges" along the way.
There are some cable manufacturers that DO pay attention to such things. They have to be WAY pickier about how the wire is manufactured, what direction the wires are laid out within the cable in regards to each other, the direction that the individual conductors are flowing when burned in, etc... The end result of all of this work is typically an increased sense of ease to the presentation with a wider, deeper and slightly higher sense of soundstage in a shorter period of time i.e. "less burn in".
I hope that some of you could follow along with what i was trying to explain. Without being able to use pictures or diagrams to demonstrate things, it can be tough to try and explain things in a fully understood manner. Sean