Honestly, I'm almost completely sure Nofap is just a meme since the "science" behind it is pretty much nonexistent. Oh, and I've gone months without fapping (unrelated to Nofap) and barely experienced any effects, positive or otherwise. Frankly, I think it's most of it is placebo and the only thing I might believe in is that it helps you with women in some ways, mainly that your horniness makes it easier to approach and such. If you're addicted to masturbation then I think it could have very positive effects on your life, but that's not the case for most men. Haven't heard of it helping with stutter, but if it works for you, why not?