I loved to use that as my opening line when I visited a highway construction contractor's office to start an audit of his claimed time & materials cost.
(Contract Change Orders are often performed at standard published hourly rates that the contractor agreed to when he bid the overall project).
But really the contractors who usually won bids did an excellent job of matching their claimed hours to the State's jobsite inspector records so I rarely found a variance. Subcontractors doing their first public works project however ... They learned to play straight real quick, because we took any variance out of the payment to the prime contractor and let him go after his sub.