The thing is no two dogs are the same...same as people.we all do things differently ,some start the dogs of young some not so young..in both cases it works for the owner..or maybe not.. myself would be very uneasy with starting the pup of with a mower though. I have never done it myself but I would think a good well seasoned mower could sicken such a young dog very fast. Each to there own though.but a do agree with what socks has said...