I see those magical words “subject to the discretion of the chair” in the second section. It seems to me that we can accomplish all our objectives by putting those words in the first part too, so it says “subject to the discretion of the chair, the witnesses from an organization be given ten minutes”.
The rule would be ten minutes, but if it were the consensus of the room, or the chair thought an individual needed more time to present, it could be extended. I think it's good to give presenters the notion that less is more when they come and they have only 10 minutes to get their message across. Then in the spirit of equality, giving your party seven minutes makes sense.
I would give the chair the discretion to extend the time from ten minutes, but go along with Mr. Stoffer's suggestion of seven.