The "house flipper" that done my MIL's house ran the typical yellow jacketed 12-2 NM, but where he needed an additional conductor for three way switches he must have figured using a single yellow
12 THHN/THWN along side the NM was sufficient cause that is what he did.
And probably why threads that come up from time to time from engineers get closed when asking about DIY projects. Some just not meant to actually do the work.
I pulled a lot of nails out of lumber from old house my parents tore down before building the one there now, I was maybe 8 years old.
You can always tell an engineer, you just can't tell them much....
And that is their job, to bring up things that are questionable, not to nit pick things they don't really understand. If they encounter something they don't understand it should just be mentioned that a professional should be consulted and not offer solutions to something they don't even know whether is wrong or not.
It is astonishing as to how many electrical engineers in this building couldn't wire a simple branch circuit and a switched light. I bet I've drawn it out on white boards at least two dozen times in the last decade. Granted, I'm the only one of them who use to be an electrician, but, schidt, it's a hot, a return, and a ground. It's far from rocket science and for the life of me can't understand how anyone with a degree in anything electrical can't understand it.
I hear ya. We had an engineer here years ago wiring his own remodel on his house. He told me that when he flipped the new light switch, the main breaker would trip. He had the black on one screw...and the white on the other. Semiconductors or high voltage, the theory is the same...ohms law applies, kirchhoff still knows what's up, and he just didn't understand why the white wire didn't have to go to the screw. LOL
But they can follow some software program logic or a somewhat complicated flow chart with no troubles, right?
My father's house was built from a tear down on the other side of town. That house was built around 1900. And electrified at some point. Dad built his house 1949/50. There were still knobs and tubes on/in the floor joists from the other house (still there when I sold it in 2012). And a lovely 100 year old 6 pane glass back door where the glass had waves in it. Ever seen a house built in 49/50 with rough cut 3 x 4 studs? Dad went to the county in 1949 for a $3000 permit, deed had a restriction the dwelling had to be $5000. When questioned, dad said " It will be built for $3000 because that's all I have, but it will be worth $5000". He got the permit. Brick Cape Cod. He did hire an electrician....
