When Bruno was a puppy, I trained him to walk by walking him with Mitzi and Judy. He learned from watching them. Now, over five years later, I tried to train Tony(almost 6 months old, about 60 pounds) to walk by walking him with Judy and Bruno, all three on martingale collars. He was so excited to walk with them, he would pull from one to the other, then around me; took me down a few times. So I took Tony alone with a short leash (about 1 foot between my hand and his martingale collar.) It was like a miracle. He was a different puppy!! He walked about a step behind me with no tightness on leash or collar the whole way. I couldn't believe it. It's a joy to walk him. We can't assume all puppies are the same and learn by the same methods.