In addition to what /u/Thorius04 already wrote, I can add these remarks: - First off, if we start substituting, we often need to start thinking of different phrasing or different sentences altogether. That's added effort - and we're already taxed by the act of speaking itself. - Second, even if we start substituting, it's not guaranteed that the words we use instead will not cause us problems - or worse, maybe we'll run into even more problems in the substituted phrase/sentence, than if we had just pushed through that one bit in particular. - Third, if we make it a habit to just dodge and weave all the time, I think we'll often feel a loss of control, which makes every interaction even more painful than it already was. But here's an important addition for the third point: If we instead get used to simply working through the stutter when it happens, and stop perceiving it as something shameful that must be avoided at all costs, then it's not as painful anymore. (This addition is why I'm often trying to push for reinterpretation of what a stutter is and how we should - or can - feel about it.)   There's a fourth point too. Substitution _can_ be useful, but I think we should compare this more to e.g. regular speakers who can't remember a word. Some of the situation we encounter have other prioritization, and sometimes we can use substitution to get a point across faster or more reliably than otherwise (stuttering through a particular sound). It's just that we shouldn't make it the default, as per the above. Substitution is more like a tool for particular narrow situations where we can't reasonably work through the stutter, and need to deliver something - anything, really - at a different pace. - Bottom line: A substitution is sort of like a "lie", and we shouldn't build our communication on "lies". We can do it once in a while, but as a habitual thing, it's most likely going to run away from us. The habits we _actually_ need are those that consistently aid us in working through the stutter, instead. Does that make sense? :)