In 1980 when I first saw a 521 almost nobody had them. Valves were found the old fashioned way with potholes and educated guesses. In some ways hunting valves down that way helped me when I started using a locator. I'll be the first to admit I've learned more about how locators work from Jim. I'd be curious to see how that would change some of my methodology but ain't going to happen. I do believe relative to those in the industry doing what I did that my customers were getting a good deal. I charged by the hour and didn't charge for the locator and in most cases it was used maybe 15 minutes or less.