My wife an I bought a house built in 1981 located in Lake County California.
I've been switching out receptacles and switches and found some "interesting" wiring. Now, these all look like "as built" items, not where the new owner hacked in a new circuit.
First: Stripping the middle of a wire to avoid a pig tail: Several 2 gang outlets are wired like this. The hot and common wires run to the first outlet, where a section of insulation is removed from the middle of the wire. This is then wrapped around the screw terminal and the rest of the run is attached to the second outlet. (Sometimes the screw terminal, sometimes the stab connector.)
Second: Using an outlet/switch as a splice junction. Here was another odd one. The switch is wired normally, but a hot and neutral running to the next box in line is not pig tailed, but taken off the stab connectors on the switch. In another, the two gang box with double outlets are wired as above, except a next in line circuit is taken off the stab connector on the first outlet. (And, to make it extra weird, the common is pig tailed.)
As I am going through, I am correcting these with proper pig tails, but can't help wondering how it ever passed inspection.