I’ve worked with a bunch of old school maintenance/fab guys in my day. One of the tests in the old days was to chamfer the edge of a steel plate with a cold chisel. Another was to take a perfect cube of steel and reduce the dimensions into another perfect cube by 1/4″…by hand filing.
My You Tube channel: https://www.youtube.com/channel/UCA5AretE3xPoVDV61AxUdUA
I don't do a fast job. I don't do a slow job. I do a half fast job.