I haven't read any studies on weekly-based therapy, but intensive speech therapy (40-60 hours over the course of 2-3 weeks) brings pretty much everybody down to mild dysfluency. It's hard to separate cause from effect, but there is a neuroplastic change during intensive speech therapy, and intensive programs cause more neuroplastic change (with other disorders) than weekly-based programs. I wrote up some advice about speech therapy in an [earlier post](https://www.reddit.com/r/Stutter/comments/pykg7q/quick_hits_what_the_research_says_about_improving/?utm_source=share&utm_medium=web2x&context=3). And for what it's worth, I got some benefit from a weekly-based program I did in high school.