My motto: Never teach what you will not use yourself to communicate? It is unnatural to talk in slow stretched speech. Try it and you will see. Watch the listener’s response. Ask how you feel…
Sometimes people who stutter are asked to use rubber bands or hand movements to stretch speech. That might help for the moment but it is not better than stuttering in the long run.
Although this helps for a short time, there is not long term research or evidence that this can be sustained. Why are we teaching this skill? Again some small amount of stretching can help but usually easy onset is better.
Honestly I tried stretching speech in my early 20s. It worked for a short time but than it sounded funny and I felt awkward talking . As one of my 9 year olds reported, “I sound like a robot and put people to sleep. I do not enjoy this anymore than I enjoy stuttering”.