With all due respect, there is no consensus on the root cause of stuttering. There is no peer-reviewed and widely accepted theory. So you're really not speaking from a place of scientific confidence when you say that something which has practically never been studied (chest tapping/chest stimulus) in the context of stuttering has no relevance to stuttering. I personally suspect that stuttering has to do with a speech control nerve beneath the sternum called the left recurrent laryngeal nerve. This nerve is involved in speaking, breathing, and swallowing. It is also associated with an evolutionary defect that all humans (actually all mammals) have. I'm not super interested in anecdotal myths about conditioning fluency/dysfluency. I don't think it is accurate or useful to have a view of stuttering which faults the individual for not "trying hard enough" or "learning fluency" well enough. I can see that you have no interest in understanding the root cause of stuttering, but thank you for your input nonetheless.