Some beginners assume that they must work toward the day when they don’t have to take any walk breaks at all. This is up to the individual, but is not recommended. Remember that you decide what ratio of run-walk-run to use. There is no rule that requires you to hold to any ratio on a given day. As you adjust the run-walk to how you feel, you gain control over your fatigue.
Learn more about training for runners in Jeff’s book Half Marathon – You Can Do It. You will find the book at: https://shop.phidippides.com/collections/books-dvds