I had a neurogenic stutter from a crash-related TBI when I was 3. From experience, it depends on certain circumstances. For example, I can stutter without my social anxiety reaching peak levels, but if the person I am talking to has strong eye contact, or if i feel like my stutter is annoying them, then I start to stutter like I am seizing up so badly. Then another thing is that when I got pulled over without having my driver's license and car insurance (twice), I somehow became really fluent and smooth with words while speaking to the cops because my nervousness wasn't set on my words, but they were more set on me not getting into more problems.