I haven't seen IT, but I have seen what I believe to be a scene from IT - the mother or a friend or someone (memory has robbed me of the specifics) is helping the child with practicing their speech. The give the child a typical "be confident" type speech, which allows the kid to be fluent. Am I remembering it accurately? If so, I don't really like this portrayal it seems to perpetrate the idea that stutters only do it because they're nervous or lack confidence, and they can easily be cured if they just pull themselves together.