Yes I have seen some stammerers speak like this. This is actually called mouth widening technique and can improve stutter. But under the hood it follows prolongation only. When we try to wide out mouth on a syllable( starting pronounced sound), we are actually prolonging it so that the word comes out of the mouth easily. So I will suggest that you practice prolongation instead of this as mouth widening does not look normal and soon you will have habit of it which will look bad professionally and personally.