I did my first jingles in 1964, using American tracks recorded in Mexico. All we did was change the station name from the "demo package" of "7-90 Radio Éxitos" to "57 Radio Musical" while keeping the phrases that the Mexico City station had in the package for "good morning" or "weekend" or "Number One" and the like.My sense was that before the advent of those short jingles, the intent was to replicate the old time radio sound when stations had in-house bands that would create transition music.
Of course, the package had originally been done the year before for WABC and a syndicated version was done offered. The dial position of course had the melody of "I love Manhattan" which was meaningless elsewhere, but catchy none the less.
We re-did the jingles for the Quito station each time WABC did a new package... even the "a go-go" set!