IO540
Whether or not the activity appears in your Narrow Route Brief depends on the scope allocated to it by the author of the NOTAM (Aerodrome, En-Route or Nav Warning or a combination thereof).
If the scope contains A (Aerodrome) it will appear in your brief if the aerodrome concerned is your departure, arrival or one of your alternate aerodromes.
If the scope contains E (En Route) it will appear in your brief if its radius of influence and height band affected cause it to cut your Narrow Route.
If the Scope contains W (Nav Warning) it will appear in your brief if its radius of influence and height band affected cause it to cut your Narrow Route AND you have selected "General + Misc" (the default) in the "Purpose" box. If you have altered it to "General" then the fact that the scope contains W will not cause it to be included. (Under ICAO Nav Warnings are Miscellaneous and so are excluded if you choose this option)
The scope that should be applied to a NOTAM is covered by Eurocontrol's OPADD (Operational Procedures for AIS Dynamic Data) which complement ICAO requirements.
Generally speaking you should not expect activity that takes place entirely within the ATZ to be given a scope other than A (although it might). Stuff that extends beyond the ATZ would normally include a scope of E or W. Anything given W is informational rather than mandatory. The Red Arrows are generally given a TRA which would be scoped E, while something like a BBMF fly-past that does not involve any airspace closure would be scoped W. Hope this helps.
In essence the advice is to trust the author of the NOTAM to scope it properly.