The most important peice of the puzzle is learning to care less about other peoples opinions of you. You can stutter all you want when you're alone, or stutter on purpose when you're alone and you feel very minimal tension. Maybe just frustration followed by anxiety about future interactions. But when you stutter in front of others it's a different story right? It's shame, and huge amounts of tension. Of course we wouldn't want to stutter if that is the outcome to how we feel after. The value you put in other people's opinions of you dictates to what level these negative emotions arise. And some other factors of course but this is the biggest one from what I've seen in my life and others.