Oh - I see. All I have ever read and learned about shooting traditional bows is that having the cock feather out is supposed to decrease interference and give you a more consistent shot. Admittedly, I haven't shot one for years, so maybe that's been proved to be a myth. Sounds like some others on here feel it's not that important.
Anothe reason I believe it was originally done was that by having the cock feather a different color, it was much easier to place the arrow on the string in the right orientation, rather than having to actually look closely at the nock. I guess once you learn "which way is which, it wouldn't matter whether it was up, down or out.
It seems to me like it would increase your fletching life, though. If one feather is rubbing the bow or shelf significantly harder than the rest, it surely would wear out sooner. With the cock feather out seems to be the least amount of rub possible for all three.

Jaybe