My dog understands that when he pulls we stop, and he comes and sits by my side. But then he pulls right after that and then will come to me. So he knows what to respond with when I stop him from pulling, but he still pulls. Again. He stops and will redirect himself the second I stop, but the second we start moving again he is pulling.
I have tried and tried to train him. He is smart so he really understands commands and understand when I stop him he needs to come to my side but that this will happen every time the leash is tight is a foreign concept to him. I am very consistent, hence the reason he knows what to do the second I stop, but it isn't helping, we just stop about every 1-2 ft (30-60 cm).
I also try to take him on many short walks, so that we can really focus on training. Also he is great at playing fetch, so I often play fetch with him before walks to tire him out, but he still really wants to pull.