[Stuart]

And a newsreader spends most of their half hour bulletin not on air anyway.

They may not be in vision, but the running order could be changing because reports aren't available, or they may be getting instructions about a developing story.  I doubt any bulletin ever goes exactly as planned between the moment they walk into the studio and when they leave it.

It's not like they're sat there in the meantime sending WhatsApp messages about what to have for tea later.