These types of devices are more useful, say, for adding an extra :30 break
during the course of a half hour program. Sales types love this stuff -
the public, not so much...TV56 used to do this on certain shows, in the late 80's.
I remember that the reruns of the show "Facts of Life" was one of them...
If you are that far off of the program schedule, normally you would join the following program "in progress", or blow off the following program entirely, and jigger the breaks until you are "caught up". (priority: paid spots run, local first, then national; promo's and psa's if there's time...) This is where it certainly helps to have a heads up master control operator!
An extreme example of this: 1981 I was working for a local radio station. President Reagan was shot. Owner/GM says "go to network". Stayed with the network for several hours. Station was a daytimer. 15 minutes before signoff time, the GM says "run all of the paid commercial spots we preempted for the network coverage". 15 minutes of commercial spots back-to-back-to-back, sign off, turn off the transmitter. If you wanted to find out what happened to Mr. Reagan, you either had to tune elsewhere (no internet then...) or catch our newscast when we signed on the next day. Welcome to the wonderful world of commercial broadcasting! ;D