One interesting note from history is that Horace Ford considered the best longbow target archer shot parralel shafts that were footed. This is the old english text from his book, Archery, Its theory and practice, Chapter V: Bobtailed is tapered, straight is parallel.
And so as regards the bobtailed arrow, which is largest at the point and smallest at the feathers, the converse of this is true. For here the tendency during its whole passage over the bow is to the right of the direction of aim, only retained by the retention of its both ends; it has a rapid flight, but docs not follow the point well and is additionally objectionable as a departure from the straight line. In short, it may be set down as an incontrovertible position in target shooting, that any shape of arrow that causes the centre of its thickness to vary in its relation to the edge of the bow, is radically bad. Therefore none other than the perfectly straight arrow is here recommended.
Current world longbow champion shooting parallel shafts? Humm?