I encountered the idea of voluntary stammering many years ago. I appreciate that it gives a sense of control and can desensitise you to the discomfort of stammering, which can be really powerful. I think you need to have the right state of mind, though. When I first heard of the idea, I was in quite a bad place psychologically, so it felt like banging my head against the wall to spite my headache. With the right psychological mindset I think it can be a powerful tool. Also, simply accepting when things are not ideal without resignation can free the mind for more productive pursuits.