Experience shows that management should occasionally make random check-ups (in person) to ensure that maintenance work has actually been done. The larger your company, the more important this becomes because of the distance that often separates workers with management.
Here's an anecdote from someone here at MainBoss HQ. Some years ago, he worked in the maintenance department of a large manufacturing company. The main shut-off valves on a particular pipe system required an annual inspection that included turning the valves all the way off and all the way on before returning them to their usual setting. Two workers claimed to have performed the complete inspection procedure, and their supervisor signed off that they'd done the work...but when management did a random check-up, they found that the valves had been painted several months before and the paint wasn't broken on the valves' screw threads. Obviously, the valves hadn't been turned at all since they were painted.
By the way, this particular plant had a legal obligation to make sure those shut-off valves worked. The improper inspection may have opened the company to costly fines and other legal penalties. This kind of risk makes it even more important to make sure that scheduled jobs are actually done. Random check-ups are one way to discourage those who might sign off on a job without doing it.