Earlier quoted context omitted.
In the 1940s and 1950s radio programs and eventually television shows were sponsored by advertisers. soap operas get their name for being vehicles for soap companies. Off the top of my head Fitch's soap company was a big advertiser in the 40s. Another big advertiser in the forties and fifties was rexall. I don't know what the return on investment was, I always figured they did it as a way to show that they supported…
I've long known this, but not how they used it to advertise -- was it product placement, pre-roll, being the only mid-roll adverts??
Then you get the intro to the show, and sometimes a product spot. Then the show starts, and depending on the format (half hour, multi-part 12 minute, etc) you may get a mid-roll and finally at the end a final sponsor message, plus the studio (like CBS) would pitch other shows on their network, and the star of the show would also have their current movies and other productions pitched at the end, as well.
Check out Richard Rogue on OTRR or archive.org for both styles, the mid-roll and the post-intro roll with jingle, it varies depending on year of production. Their main sponsor was Fitch, as far as i can tell.