You get to throw a lot of tees in until it even begins to approach rubbing your robe clean down in the river.

And setting on laundry is largely a fixed effort, whether you do one item or thirty. Most people don't do one at a time.

I do my laundry once a week if not more frequently with a decently heavy load. I don't go down to the river, but I've lived in apartment complexes where the laundry room was a few hundred yards and several stories away. You still do some stuff on per clothing bases, like folding, ironing, special care like certain things being air dried on hangers or some other surface. Some stuff washed cold or hot even. Some people have to shlep their stuff to off site laundry businesses much a kin to a walk down to the the river. I'm sure back then you'd only be washing a handful of thin linen underclothing regularly, outerwear if at all. These people back then also probably weren't washing bedding. Some doctors say the modern beds, while comfortable, are worse for the spine than a firmer surface still used in some cultures.