It's tricky to walk two dogs - who are still in loose leash training to varying degrees - on a loose leash when on our way to an off leash run. So, I have one or the other on a management halter, and train the other one. On the way home, they walk in beautiful unison right next to me, with hardly a treat necessary by now - that's when people should look :-)
When teaching loose leash walking, using a management halter (either a body halter of some kind, or a head halter) is indispensable. Why? Because it's impossible to train a complicated behaviour such as walking on a loose leash in all circumstances properly for the extended time we usually take our dogs for walks. Most of us don't have our own acreage to exercise our dogs, and have to walk our dogs for that purpose. When you are first starting on loose leash training, you don't get very far before both you and your dog have had enough. If you always make a careful distinction of what rules apply when, your dog will pick it up in no time.
Giro for example nearly always pulls in his head halter, and completely ignores me. Even if I say his name, he reacts slowly, almost suprised to hear me talk to him. This is because from the beginning, the rules were that if his headhalter is on, there are no treats, he can pull and we just have to get there. Switch to the collar, and he's a different dog instantly: Attentive to his name, and instantly coming back to my side should he feel pressure on his collar.
To be continued!