Up until the 1950s....this ‘short-wash’ thing was a normal thing for German households. Then hot-water heaters came out and bathing a couple times a week became the norm.
I will say that prior to this whole Ukraine/Russia thing...there were German health-experts saying a full-up bath every single night was absolutely not necessary.
On personal saunas? There just aren’t that many Germans around with their own sauna. I bet it’s only like one house out of a three-hundred with this feature.
A lot of upper-middle class households have them.
There are namely prefabricated ones you can buy and set up in your basement in about an hour.
Yes, these are dry saunas I'm talking about.
Regards,