When practicing I unsheathe my weapon and set the scabbard/saya aside. As I said previously, having it flop about all over the place is cumbersome and annoying.
That was usually the case, historically, to be honest. If you're taking a hike, like it was mentioned few comments back, or riding a horse, you either strap it to your horse or carry it by hand or your arm, or beneath your armpit, like you'd carry any other weapon.
if you're finna use it, then just unsheathe it and throw the scabbard on the ground, pick it up after the fight and carry on. There's no pratical use in using a back-scabbard except for the weight, but it'd rate your chances in a fight or getting caught by surprise unfit to fight or atleast at a disadvantage, that's just a movie thing and even if you can (shown by Shadiversity, which again, is not pratical) you can still just use your own sword belt to just wrap it around your arm or shoulder like you would a rifle or something, there's 100 better ways and simpler ways to carry a sword instead of on your hip.
Once you're stopped or camping out in your journey, you'd only need to unstrap your sword from your garments belt and either rest it by your legs, chest when sitting down or simply rest it by your things/pack, but your sword is always with you either way.
Anyways, I think the whole sword/sheathe has been already answered by Cowboy, but yeah.