Turns would have varied through the years with some being 24-hour and others only for certain hours of the day.
But you only have certain hours in the day to do business.
But now our daughter can't believe that we want her home at a certain hour.
He would probably return, by a certain hour, in the afternoon of the morrow.
The house and grounds are open to the public at certain prescribed hour.
They will anyway at a certain hour, which isn't far off now.
She said the entire family looked after the children, who were always expected home by a certain hour each night.
Even so, most of the capital city slept during certain hours.
They had a timing that caught the eye and held it; but only at certain hours.
He and his crew seem to keep their women on the side, reserved for certain hours.