Kelly,
I agree with you that no line arrow should ever be pointing any direction but to the closest exit. However, I believe what is taught in lost buddy drills and in lost line drills, is to place an arrow on the line. (the NACD Cave Diver Workbook from a few years back says to put an arrow on the line for lost buddy drills, and does not say to do the same for lost line drills. I believe I was personally taught that in a lost line situation, you should put an arrow on the line. This will let others see which direction you went, if they come to your arrow in their search for you. It does have the hazard of potentially confusing other divers. But, a standard cookie will not tell a searcher which direction you went (note: the arrow is always supposed to point the way out, but odds are, you are heading out at this point, which is why the way you went and the arrow direction are assumed to be synonomous). Supposedly, if you went the wrong way, you'd run into another arrow which would correct your direction of travel, and when you got back to your arrow, you would flip the direction around. Any diver who was confused by your arrow, you would have presumably intercepted once you turned around.) The arrow should always point the way out, but I believe an arrow, or some directional marker, should be used in this situation. As I said before, it will let you know what you were thinking when you dropped it. If you get further disoriented and come back to the same marker, it can be important to be reminded of what you were thinking before. I do agree, an arrow will have problems if it is pointed the wrong way, but in a lost buddy situation, it should be pointing the right way. It is only during the lost line situation that I could imagine a diver getting confused and putting an arrow facing the wrong way.
In every stressful situation I have been in, I was capable of looking at the arrow and determining who it belonged to: me, my buddy, or the cave. If I couldn't look at it, I was able to feel it and know it wasn't mine or my buddy's, but the cave's. But I do know there are divers out there that don't pay any attention at all to arrows they pass, and everyone can react poorly under stress.