[Neil Jones]

I must be missing something because I don't quite "get" the concept of pre-empting something, doesn't that just reduce the net audience reach on the network broadcast if something's aired out of sync on some affiliate somewhere?

I know America runs on at least four time zones and there is a concept of timeshifting stuff live in the east of the country so it goes out at the same time on the west coast (for example and for the most part, the obvious exception being live sport), but that's not the same as pre-empting, surely?