theres no hard fast rule that I know of that says it HAS to be perfectly aligned with _______ and _____ to look proper as far as I know its like everything else....where, and how you want
FWIW; from the Regimental Drum Major Association:
"Leading edge of front flash to be vertically up front of leg bisecting the top diamond of the hose.
Worn inside hose of right leg in center of front-right portion of leg bisecting the flash with handle only showing.
Scabbard and metal trim concealed by hose."

If worn this way, the sgian ends up in the groove between the tibia and muscle (tibialis anterior), which might be more comfortable.