Agree with your method of boiling the water for a longer period of time, but this doesn’t have much to do with handling milk.

You generally don’t want to bring milk to a boil as it creates a film on top and modifies the taste. Instead, you heat it to 162F / 72C to kill the bacteria and cool it down as quickly as possibly. There isn’t a “traditional” method going back generations, since it was only in the 1860s when Louis Pasteur invented pasteurization.