Ok, i am going to land on both sides of this. I regularly have blocks where i can't get any words out (and this only happens when speaking slowly). Also, sometimes when speaking slowly, I'll stutter/stammer/stumble over my words. But, i KNOW* i tend to speak very fast sometimes and then start to trip over my words like someone running down a side walk and tripping over each slab that has been lifted by tree roots! And this is ALWAYS driven by my mouth not being able to keep pace with my racing mind!* --- *The note here is about my recent diagnosis of ADHD: I've been taking Adderall for about 5 months and it really has helped me with my racing thoughts, and i can often recognize when I'm speaking too quickly and i can now stop myself, take a beat, start again slower. This has no impact on the aforementioned blocks, but i know it helps me slow down (when speaking) and as a result, the stuttering/stammering/stumbling is reduced (but not 100% eliminated)