Stutters vary immensely person-by-person and there is a giant lack of research to create common phenotypes despite the commonality of it as a disorder. I don't think solely repetitions by themselves are necessarily common, but not outside the realm of realism. I also echo the sentiment of other comments mentioning how different traumatic brain injury stutters can be (not an expert on this, as mine is neurological afaik) My advice personally is... don't write stutters. Now, you can write a character with a stutter, but writing it out in sentences probably won't fit. I know that this isn't the answer you wanted, so let me try to explain: When someone stutters, they are not saying "bet-better". They are saying "better" and making a non-verbal sound that *seems* like "bet" before hand, but it's not an actual word. Now, think about this concept of writing non-verbal sounds, and you quickly realize that the way people write isn't at all the way people talk. Listen to someone talk in real life. They probably use a ton of fillers, such as "um", "uh", "like", etc. You can expand that concept to realize that people also mispronounce or misuse words (which is closer to what a stutter is then specifically saying the word "bet-better"), but that's never written; i.e. have you seen people write "anyways" instead of "anyway", "gonna" instead of "going to", etc? Maybe in some cases, but not commonly; most writers write how characters are supposed to pronounce things (non-stutter), not the way that they actually pronounce them (stutter). So, unless your work consistently writes out non-verbal sounds and phonetically writes words, I wouldn't explicitly write in stuttered words unless directly relevant to the sentence (i.e. the reason that someone would misunderstand the character). I support you in writing the character AS a stutterer, though!