Following on from Mutt's comments, it is accepted that limitations and regulations are prescriptive while remaining material is recommended.
One needs to have made due consideration of the OEM's recommended practices but there is no magic formula which says that an operator must operate strictly in accordance with the OEM's way of doing things. Indeed many operators over the years have made an art form of doing things differently according to their own perceptions which may vary according to who is in the chair from time to time.
NTO is a traditional way of seeking OEM de facto concurrence with alternative ways of doing things ..