With the wider ribbon flashes (made of 2 inch grosgrain ribbon), if you put them on just below the knee where your shin narrows, then place the leading edge of the ribbons near the front centerline of your leg (or following the shin bone), then the trailing edge of the ribbons will be close to the centerline of the outside of your leg. This will put the centers of the flashes close to the 'ten and two' previously referred to. (I then tie my ghillies in line with the flashes, about two inches above my ankle.)

Putting them on so that the center of the flashes is on the centerline of the outside of your leg (where the calf muscle is defined) puts them too far back. The trailing ribbon will likely wind up draped partly over your calf.

Similarly, putting them too far forward will wrap them around the front of your leg.

(This all depends on just how big your legs are.)