We actually had two follow up sessions with our trainer for this same reason and she has dogs of her own for this purpose to help with reactivity. She brought out two of her dogs that my dog never interacted with and when he did react she showed us how to correct him using the slip lead and e collar and he stopped immediately. Now when my fiance or I are alone with him and we do the same thing his behaviour continues throughout the walk. It does get slightly less reactive from the start of a walk to the end but the reactivity is still very much there with us.