At one time ( late 50s), Luxembourg djs would start playing records without introducing them. The dj would then fade in after about 15 secs and give the title.
Me and my mates would play a game whereby we had to say the title/artist of the recording before the dj came in.
Also, if I remember correctly, in those days the only the first minute or so of recordings were played before being faded out ( I know some single were very short in those days, but out that short!).