If they need a response within an hour, then they need to indicate that (and ideally why) in their initial contact.
If they expected a response within an hour and didn't get it, they can call me or physically come to me.
I've told two of my bosses while being interviewed: Assume I'll check email only 3 times a day. Is that workable?
No one says "No" (even though it may not be workable).
One of my bosses actually suggested to me that I should have "office hours" and be available in those hours, and simply not respond all other hours.
It all depends on the need of the job. And most engineering/SW jobs do not need you to "be available to respond within an hour" for any request.
