Why blank tracks at the end of audiobook CDs?

Just listened to Simon & Schuster’s 2006 audiobook of Ernest Hemingway’s A Farewell to Arms, on eight CDs. A great book, and well-read by actor John Slattery (Mad Men, Spotlight, Ed, Flags of Our Fathers, etc). However, unlike every other audiobook I’ve ever heard, each of the CDs had a silent track of 15-20 seconds at the end. The blank or silent tracks were numbered just like the others with Slattery’s narration.

Why’d they do that?

Perhaps the tracks were planned at some point, for example some kind of advertisement, but it was later decided they didn’t need them so no audio was recorded for them. It might have been easier to just leave them there than to remove them completely.

My guess would be to tell the listener the CD was over and to switch CDs without that annoying CONTINUED ON DISC 2 track. Since a lot of CD players have REPEAT ALL modes I can assume a track of silence to notify the listener was a better compromise than either the CONTINUE audio or having it immediately just restart the first track leaving the listener confused.

Could be, but I’ve listened to a lot of CD audiobooks, and this is the first time I’ve seen this.