Another interesting thought about WPVI: they're switching their digital channel back to 6, which means they're going to go through complete disruption, unless they've got fiber feeds to satellite and cable.
This probably explains the 12:15 time. This lets them do a "special edition" of Action News at Noon, getting in a few stories, some commercials, and then the switchover, reminding people to re-tune their digital boxes at 12:30 after the adjustments are complete.
Of course, if the adjustments AREN'T done by 1, you're going to have a lot of angry "All My Children" fans out there.