It absolutely breaks my heart to read such terrible advice.
Novus is an ABRASIVE that wears away the protective finish of a playfield. It's meant only for plastics like ramps, posts and the tops of light shields. You may not see damage now, but check the key lines around the inserts after a few treatments.
As was mentioned above, Naphtha is good for cleaning rubber and removing wax, but shouldn't be used as a general cleaner.
Light application of a degreasing cleaner and quick removal with a clean cotton cloth is enough to clean a play field. Then apply a coating of carnuba paste wax.