In the 2000s I had a SaaS firm making software for underground utility locating companies so I learned a lot about the industry. In most parts of the country as built drawings are unusual for residential property anyway. Locating staff mostly shows up, looks at whatever drawings are available, and then has to figure out what was actually done from the clues and by using locating equipment. Many of these folks end up with a very subtle understanding of what common practice was by different utility companies in various specific areas in specific eras.