Could a dialect coach or vocal coach help?

Could a dialect coach or vocal coach help? I've heard of actors using dialect coaches to help them change their accent if they can't go back to their normal accent, for instance, Austin Butler can't shake the Elvis Presly impersonation and is using a dialect coach to help. I know it's not the same level but with a dialect or vocal coach, they help change the way you speak. Would that or has that ever helped anyone with a stutter?