I wouldn’t go as far as saying the terriers Where better, when u put the dog to ground, he doesn’t know if he has a locator collar on or if it’s 2ft or 20ft deep, if the terrier wants to stay it will stay I believe. As for the terriernen back then, as said yes, there was more to take into account than just drop dog and wait in numbers to stop on the box, but doubling up was very common although nobody likes to admit it, but modern day technology has (hopefully) removed that practice. But take into account all technology fails and I have dug a few dog out without using the the locator, cause