This is also called negative practice. It can be a highly effective approach to increasing fluency. Stuttering is in part an approach-avoidance problem. You want to say something, yet at the same time you want to avoid stuttering and block or have repetitions and so on. By trying intentionally to stutter you are neutralizing the “avoidance” part of the equation. By trying intentionally to stutter you are neutralizing the power stuttering feels like it has. It desensitizes you to the emotional part of stuttering. You can stutter and stutter fluently, rather than struggling and having severe blocks.