The user hour analogy sounds weird tho, 1s feels 1s regardless how many users you have. It's like the classic Asian teachers' logic of "if you come in 1 min late you are wasting N minutes for all of us in this class." It just does not stack like that.

If the class takes N minutes and one person arrives 1 minute late, and the rest of the class is waiting for them, it does stack. Every one of those students lost a minute. Far worse than one student losing one minute.