cable directionality

I've always heard that single-ended, directional interconnects (e.g., AudioQuests) should be installed with the arrows pointing away from the source. Is that really true, though? It seems like it actually doesn't have much to do with signal travel, but with grounding: normally, the shield is connected to ground at the end the arrow points toward. Therefore, it seems that the cables should actually be installed with the arrows pointing toward the system ground (normally the preamp). This makes a difference (or does it?) for the cables between the preamp and power amp. What about directional speaker cables? Should the arrows point back toward the preamp, too?