My understanding is that the latter half (ish) of the main 30-minute weeknight ITV News Calendar is a single live pan-regional edition. Even though all other bulletins produced are two separate sub-regional editions (one live, one pre-recorded shortly before broadcast), I'll wager that a bit of story-sharing occurs thus creating an overall pan-regional/sub-regional compromise in terms of content?
Conversely, the BBC's Leeds & Hull regions I believe stick to rigid editorial boundaries (in common with all other BBC English Regions). This I understand means (or at least has meant in the past) things like Look 'ULL won't mention Yorkshire County Cricket in their sports news, because the team/ground are based in the North Yorkshire county (which is not part of the Look 'ULL region). Never mind that the cricket team represents all four Yorks counties, and therefore is equally of relevance in ERoY...
If ITV recognise the value of not arbitrarily cutting across areas of common interest in this way, I'm at a loss as to why Auntie Beeb fail to do likewise.
I could charm the vultures off a corpse.