Just had an abstract thought;
I know a lot of English Longbow archers, here in the UK, use a rubber 'O'-ring slipped down the top limb as a sighting aid. The idea being that you slide the band to the correct placement on the limb & then line it up with the target.
The principle is so simple it's brilliant, infinitely adjustable, always there & cheap or free to replace. Does anyone else around the world do this, or is it a quintissentially 'English' thing?
(Personally I don't do it, just interested! :D )