Then there is an equally accomplished Arvind Subramanian, the Chief Economic Adviser to Government of India. Whether you like economics or not watch this joint interview. No, I am not trying to pit one against the other. Rather I want you to observe how these two men speak.
As a young professional, I once attended a public speaking workshop. During the workshop, we had to make presentations. I had assumed that I was, if not accomplished, at least a confident speaker. I was in for a shock, the feedback from the trainer crushed my confidence. He pointed out that between each sentence and within them, I had used many aaa's (read stammer), elongation, and pauses. If you still can't visualize, notice the difference between the way the Governor and the Adviser speak. While the latter uses a lot of extensions, repetitions, pauses and hesitations, the former's thoughts flows like a river. He doesn't pause, there is almost no stammer.
What does stammer and hesitation or their absence indicate?
If one is able to speak without any pause or stammer it indicates mastery over the subject. The rate of delivery and the rate of thinking are in sync. They buy time for the brain to formulate the thought to be delivered. Imagine them to be the hourglass icon or rotating circle which appear on your computer while it loads.
According to my candid trainer, they are to be avoided. They are not acceptable.
The French are different
So, to stammer or not to stammer?
Personally, if I am aware of an answer my brain would not require the time to formulate it. Of course, then there is preparation. Preparation can train the mind and ensure elimination of the thinking process. And here is why I love Raghuram Rajan. Even when posed a question on dosa and economics, he doesn't seem to consume many pauses. That certainly reflects his comprehension.
To answer the question as to whether stammer, hesitation and extension is acceptable, it is no. At least as far as speaking in English is concerned. And certainly not in the corporate world.
I presume a state of speaking coherently comes with in-depth acquisition of knowledge, understanding of its implications and honing of articulation skills.
As for me, I don't foresee reaching that state in near future. D'où, I seek refuge in French.