I'm a slightly forward wearer. It's just the way I've always done it.

Not saying it's right or wrong but here's the way I think of it... much like an improvised First Aid arm sling, when you tie it around the neck you place the knot slightly to the side of the neck to avoid pressure on the neck. The flashes / garter ties are much like that in that historically there would be a knot at the point where the loose ends of the ties would be hanging from under the hose. I would want that knot to be on a more flat part of the calf than on the widest, apex on the side of the calf to avoid concentrated pressure on a narrow spot.

Also my sgain dubh rides at about the same spot because it's more stable there and having the sgian dubh and flashes maintains a sort of military alignment.