should I suspend a floor-standing turntable?

It varies, in apts electric is usually in half-moon pipe strips running up the wall painted same color as wall, you hardly notice them. Most rewire every 20 years.most sockets look like Hubbel grade .
Average German house has 2-3 foot space between outside and inside walls with cylindical terra-cotta round pipe between them.Walls are plaster over wood.
I live near one of the most up-scale suburbs in the twin cities and it amazes me that houses going for 750K use same
drywall as a 100k condo.

Schubert, yeah, here expensive houses have nine foot ceilings rather than eight foot ceilings, and really expensive houses have eleven or even fifteen foot ceilings. But all are drywalling, usually using eight foot tall pieces. But we had friends with an old house where the wall were just laths with heavy wall paper glued to them. You could see them move when the wind blew. I guess it must have been like heating a tent in the winter.

Yes, I owned a house like that in VT .Oil man loved us.
Back in the day you had to have money to plaster, in rural areas at least.