You didn't offend me, and I could tell you weren't meaning to demean physical labour.
> I'm not sure if there's a corresponding mental equivalent to muscle memory.
Have you ever driven to walmart, or work, or your girlfriends (someones) house when you was slightly distracted when driving. You don't drive dangerously, you're not swerving of being stupid like if you was drunk or distracted, you're just not thinking and you end up going the wrong way or doing the wrong thing. There's been a couple of times in the morning when I've accidentally changed the time on the microwave, because I always used to have to hit the timer button before putting in the time. Now I don't, but on autopilot I can somehow manage to find 'time' on a different keypad layout and change the time to 1:30.
I agree with the second, having a tactile object to work with seems to free up a lot of the cognitive ability for the task at hand. Although, when I was doing electrical work you often needed that mental model to know where wires were running, so stepping into someone elses job (especially when it was done wrong or poorly) was a major head-job.
> I can go back in and redo it at basically zero cost
That's why I write fiction, because as a professional career it's only loss of time that matters. Thankfully in my job (vinyl siding) my materials are fairly cheap, so waste isn't a huge concern for us (but a good worker always minimizes it, like unless you're confident you use a piece that's already garbage to make a template rather than wing it on a new sheet) because our company gets paid for our reputation and how presentable our jobs are (there's a big aesthetic difference between done and done properly).
> Like I said, I've seen enough experts in action to know the difference isn't in the hands.
That's in all jobs, I've seen my fair share of talentless doctors, etc. (At 15 I called a doctor out wrong when I self diagnosed psoriasis, the hallmark is scaly skin that pin-prick bleeds when scraped and I had it and I had psoriasis, but that doctor couldn't admit he was wrong to a 15 year old)