Back in 2019 I was that guy checking every shaft with a $40 pair of calipers and feeling pretty good about it. Then a guy named Ray showed me a mike reading on the same part and my calipers were off by almost two thou, and this was a part I'd run maybe 200 of. What got me was his point about feel: your thumb pressure changes the reading every time, so you're not even measuring the part, you're measuring how hard you squeezed that morning. I still grab calipers for rough stuff and checking a length before I cut, but for anything with a real tolerance it's mics or a bore gauge now. Took me a while to come around but Ray was right and I was just too proud to hear it.