If that were true, people wouldn't stutter at all. Young kids, by the time they are in preschool, have uttered a million words. Most of which are fluent since kids who stutter don't stutter all the time. Yet, they still stutter. Good therapy isn't about practicing speaking so much that stuttering goes away. good therapy is about learning to decrease negative reactions (physical or otherwise) that make stuttering worse. Good therapy isn't about 100% fluency, but more effective communication. Fluency is a part of that, but it's a by-product of working on other things. You can't train fluency directly. it's an exercise in futility and only makes the reactions (the things you can control) worse.