Keep in mind they can afford a quality speech therapist every single day and on call 24/7. Doesn't sound that amazing. I have a stutter but only my family/close friends know I have it. I speak to like a hundred clients per day for my job and don't have many slip ups, and when I do slip up it doesn't sound retarded like g-g-g-g-g, it's minor. I've found the best techniques that work for me but I rotate them every few days and this stops my brain adapting to them.