Heard about a buddy who had to fix some of that in an old place. Said he spent a whole day just trying to find where one line went. It was a total mess.
Reminds me of my friend's old house reno. He traced a wire from the attic down into a closet, only to find it went through a hole in the floor and just... stopped. It was snipped clean off behind some drywall. He had to open up three different walls just to find where it picked up again, which was in the basement next to the furnace. Total wild goose chase.