Yeah, now remembering further, I do recall some of those booth announcers on ABC/NBC doing the plugs. They were sually the case of the ABC guy / Brandt/Wendell/Pardo doing an aside after reading off the "Tonight on ABC/NBC" with the "Now stay tuned for Super Password with guest stars..."
Back in the 60s, at least on NBC, the show announcer would do it. I remember watching a Hollywood Squares ep where Kenny Williams did it.
Even though I don't recall any of the surviving eps of 3oaM having it, I swear I've heard Don Pardo saying "Stay Tuned for 'Days of Our Lives'" at one point in the run...although it is plausible he was in the live booth announcer seat while 3oaM was on and he he said it then.
Jay Stewart did it on
Let's Make a Deal on NBC in the 60s. I remember because my grandmother would hear him say 'stay tuned for
Days of Our Lives, next in color on NBC' during that era of LMAD (until LMAD left for ABC). Before 1965, he'd plug
The Doctors, which followed LMAD (pretty sure that was the schedule then). I'll have to listen to be sure, but did Johnny O ever plug
Edge of Night following daytime TTTT on CBS in the 60s?