954 Hi Maria,
It should be fine continuing to walk Cobbler in town with muzzle as long as he is kept under the threshold of what makes him act aggressive, otherwise it has opposite effect of “socialization” and reinforces patterns of behaviors that in his mind work for him. If the walks are non-eventful it helps to show him that there is nothing to worry about.
The reason why I remove some dogs from those situations is that some of the hardest perception changes cannot happen if a dog is stuck doing the wrong behavior. That is why “perception” is above “obedience” on our self-help plan. Obedience gives us the authority to say “no you cannot do that behavior, you will do THIS behavior instead” but doesnt change the dogs perception in itself. The counter-conditioning that can then take place or desensitizing can happen at a more rapid pace when the dog can be put in the harder situations that would normally cause an aggressive response. When the dog is acting aggressively they cant learn that it is not needed, since the behavior in his mind works for their purposes and is self-fulfilling. Whether someone backs away or he is pulled away it kept him and you SAFE in his mind.
You can train all the commands at the same time and at different phase levels as long as the previous phase is understood for that command. How long you train for and how many sessions really depends on you and your dog. Many short sessions (few minutes) is always good, but longer sessions at an easy pace can also work. You mostly judge by reading your dog. Training DOES mentally drain them. If the dog seems to get a glazed look over on his/her face, starts panting (when there was no real physical reason to do so), or start to get sluggish try to end the session quick on a good note. Normally try to accomplish something with the dog and end it before it seems to be too much. I hope that wasnt confusing because it really does vary.