Techniques are band-aids to a larger wound. They will work at times, but they're still techniques. The real problem is the emotion that comes up when starting to speak, being immediately suppressed because it's too painful to bear (fear of being punished for making mistakes for example). The only way I finally learned to stop stuttering fully, was figuring that specific emotion. And you know how it went? I just tried to speak with the intention of no external validation and just trying to say what I really wanted to say. And it was just tears and sad emotions for months. People stutter because they remove the pure emotion from their speech and then try to use techniques to sort of regain it. Our body doesn't work like that, you'll only become fluent if you get back into learning to really express your emotions.