Where does the phrase "a locksmith is a slow fitter and a slow fitter is an electrician" come from?

This sentence comes from a mechanical processing factory. The lathe operator should mark the lathe tool to this position and stop immediately, otherwise it will be a waste of effort. Besides, if a lathe worker wants to work, he must work fast and hard. The fitter's job is generally to file, polish, and some even scrape. It's a slow job, and it's no use rushing. The electrician said that the general circuit is not easy to go wrong, so the electrician wandered back and forth with nothing to do.