When I worked at a station that ran Casey each week the new show would overwrite the show from previous week, but the file number was the same and the log was identical each week. This was still when the show came on CD and we ripped it into the system every week. A careless production job could result in a segment (or more) from the previous show remaining even if the log looked accurate.
It is similar now. Premiere uses the same "cart numbers" week to week, but matters are complicated in that the classic replays now have "B" shows for weeks when the replayed show is from earlier in the decade (the "B" show is from the later part of the decade) for stations that feel those older songs are incompatible with the regular playlist. I happen to be programming one of those stations, and I feel the 1980-81-early 1982 period was far too top-heavy with AC and Country crossovers to be meaningful to our audience ... so I always run the "B" show when offered. That means
two logs and it is my responsibility to make sure the right one is incorporated into the Sunday master log every week.
Fortunately, the production director at the station also knows this and always downloads the right version from Premiere. (I think he goofed once in two years.) So your comment on careless production is indeed an important part of the recipe, and I appreciate your bringing that up.
The key is that we make the effort to execute the program airing properly, and mistakes such as have been described is just plain sloppy.
If it's not sponsored why put it on the air? Another question how hard is it to put a start and end date on a file?
Automation systems, contrary to popular belief, do not check for start and end dates on individual audio files. There is a responsibility for programming and traffic to give it an accurate log to run; from there, if the logs calls for "20907" it looks for 20907.wav and plays it.
And, just for the record: I am in a position where we have advertisers who are guaranteed positions in AT40 (and we are about to up that ante by adding TOH sponsor billboard copy) so I am motivated to give them the best presentation possible to hold the audience long enough to hear their spots.
But, as David, BigA, myself and others have said repeatedly in the past, on weekends it is often better to run syndicated programming rather than have the existing staff (or, in the case of the group owners, a staffer in another market) voicetrack. In actual practice, more can go wrong with Tracking than can go wrong running four hours of At40.