While I can't say that ours have learned to CONSISTENTLY heal & walk without pulling for the ENTIRE walk…I have used some techniques to help them focus on me for most of our walk time. And I have to say that for me, it's good enough. My TOPAZ is GREAT on a leash...and well C3PO will just never be great :(. He may be OKAY at best LOL LOL..anyway here it goes.
First I would UP the treat value. Maybe PB is just not enugh to get his attention...and I would also ONLY use this SUPER HIGH VALUE TREAT when you're on walks. If he gets it any other time then the treat will lose its value. At least in my experience this is the case. So maybe you can try salmon, or tuna or smelly cheese you get the idea...
When I see a dog, squirrel, or some other big distraction..I start to say "FIND IT!" "FIND IT" "FIND IT" dropping treat bits on the ground so that the treat falls right in front of them one after another like rain drops...they don't have time to look up becuz their nose is GLUED to the ground looking for the fantastic treats on the ground. This works most of the time.
Other times I need to put the treat right at their nose...like a lure to help them focus on the treat rather then the dog.
This is all done when "watch" technique is not working.
Good luck! And let me know how it goes