I, too, am happy with my colleague Peter's proposal, because it clearly indicates—and I have had the opportunity to take the chair on several occasions—that the procedure is nevertheless at the discretion of the chair.
There can be situations for one reason or another, in exceptional or specific cases, where 10 minutes is not enough. In general, it is. The other advantage is that it allows for a better exchange. The witness is not necessarily here to make a speech; the witness is here to converse with committee members.
The more time we have for an exchange with that person, the better it will be for him or her. In fact, if we allow 30 or 40 minutes for the presentation, the witness will not be better off, in my opinion. So I am very comfortable with the initial proposal.