Simply put, leash pulling is a symptom of an underlying problem: over arousal and/or stress.
So, if you address only the pulling problem, it’ll keep coming back unless you address the underlying cause.
When you follow a dog on a tight leash, you’re training them to pull. They are learning that if they pull hard enough, they get a big reward: moving forward. But, pulling is uncomfortable for the owner and the dog. A dog that pulls on a leash is more likely to become over aroused on walks because of the tension on their neck or chest causing them to bark and lunge at other dogs/people. By walking on a loose leash, a dog learns to control their impulses and behave in a relaxed and calm manner.
What do you do if your dog pulls? If your dog pulls ahead and the leash becomes tense, simply stop, encourage your dog to come back by making sounds or calling their name, take a few steps back and when the leash is nice and loose continue walking forwards. If the leash becomes tense again, rinse and repeat. Another technique to use when the leash becomes tense is to stop, turn around and continue walking the other way. Don’t forget to reward them for walking with a loose leash and staying with you if you stop walking. Pro Tip: Practice indoors first with no distractions, you want a strong foundation of the behavior of ‘being next to me is the best place to be’.
Remember, pulling is a symptom of an underlying cause: over arousal and/or stress. Treat the cause, not the symptoms.
Disclaimer: I am not a professional dog trainer.