The company that I work for provides services to monitor generators and we work closely with a company that provides maintenance on the generators. It is a recommended practice to start those generators at least once a month, allowing the switchgear to transfer the load from utility to the generator to make sure that all of the systems are working properly.

It is not unusual for customers to end the regular test periods because of the cost of fuel. I am aware of situations where generators have sat for years without any tests or maintenance and then, surprise, they did not function correctly when they were needed in an emergency situation.

I kind of equate this to taking regular database backups, but never restoring them to ensure that everything is working. It's easy to say that you are covered in an emergency, but you better be able to follow up.