Is it not 'Airmanship' to advise an ATC sector as soon as practicable if you request a level differant from the one originally filed for?
I think the key thing is here is that as flight crew most of us don't know how the cogs will turn in the background for each sector that we speak to. For example telling a London TC controller you want FLXXX to cruise will be a wasted breath however not everyone knows that telling a TC controller this bit of info is wasted airtime. For pilots a London frequency is a London frequency and thats it! Not everyone is a sad **** like me who knows which sector I am speaking to before I key the mike!