[was_boring]

> Is this sharp control over timing something in American culture?

Probably. It's viewed as respecting others to make sure the time allotted doesn't go over. It also allows other people to better plan their day. As an American, when I run meetings they end as close to the pre-determined time as possible, and better if earlier. If there needs to be something else said, a follow-up is scheduled with only the interested parties.