It comes back to what WN said.
If its in your manual, that manual is approved by the Authority. It therefore becomes a requirement of the Authority.
the trick is to only put in your manual:
What EASA (or the appropriate Authority) specifies as a 'requirement' ( not recommendation!)
What you decide YOU WANT/REQUIRE.
Some DFOs have been known to insert their own personal "Top Tips" without realising that they are effectively making them a requirement under their Authority.
The Manual is audited against the Regs.
The Operation is audited against Manual.
