I wish it was this easy man. But no I’ve never heard of that rule but if I’m pretty sure it only applies to breaking habits. Unfortunately stuttering is a psychiatric disorder and can’t be broken like a habit can. There are many different methods of speech therapy that can help you out. Some people get lucky and they can really reduce their stuttering drastically with strategies but others aren’t as lucky. So in order to live your life to the fullest, embracing the fact that you’re a person who stutters might be the way to go. Own it. Stutter in public. Screw everyone who says otherwise. You can do whatever you want to do.