I'd say that most stations these days, whether its community or commercial, are more often than not are broadcasting voice tracked or pre-recorded shows. Breakfast is the one show that has to be live, yet Drivetime can be pre recorded a few hours beforehand but with live traffic inserts. Sometimes when the news is playing over music, its because its likley that someone hasn't back timed it properly and the playout system that could be Myriad, Winamp or RCS hasn't kicked in in time which has them leaded to an on air mess.
As far as I know the presenters at Global don't drive the desk themselves, it'll be someone in the back office - the presenters job is to read from a predifined and pretimed script which is why the likes of Capital, Heart and Smooth sounds in your face. The same will be also be done at Bauer, UKRD and the other commercial stations.
The specialist shows that I've done for community radio were done in a similar fashion but with more personality but still read from a self written pre timed script which meant any links that I performed has to last for no longer than 120 seconds and were more often than not pre recorded and hosted generically (since the shows were syndicated) so that stations that took them could plaster their own branding to it without me having to mention it vocally. Specialist shows have more flexibility since its highly likely that they'll be pre-recorded and not live.