I wasn't sure where to put this as this could be at40 or ct40 related but so far I only know of stations that did this with ct40 and other 90's countdowns that Casey did. We had some local stations that on newyears eve during the ww1 years would rerun year-in specials. One of our stations WNCI, instead of during their own year- in countdown would rerun the ct40 year-in countdown in both parts starting at 4:00 pm every newyears eve and it would end around midnight. I'm wondering was this a deal that stations had with ww1 or was this up to the individual station?
Most likely it was either written in memo or implied that you could run the year end shows as much as you wanted as long as at least once you ran the network spots on both parts. So, for example we had stations that would air the show in its normal times on the weekend and then. Ew years eve/day they'd run it in its entirety. As long as the network spots ran over the weekend, they could do whatever on other airings.
I remember seeing the first couple years of AT40 going to a 1 week 8 hour version. It was told to stations they could run it all together, in 2 parts, at a special time, whenever but they HAD to air the entire 8 hours complete with the network ads. Ultimately that's all these networks care about.
I also saw a 1993 Dees YE show case it came in. It specifically said you could run both parts together or separate. They didn't care either.
I can't say it was commonplace, but this probably happened more often in smaller markets, but not entirely. I do remember K92 Roanoke doing just that w/ CT40. I remember WFVA FM(now B-101.5) Fredricksburg airing AT40's Top 100 of '85 several times over new yrs wkend.
Shifting gears to Rick Dees, ONE time, Z104 DC aired Ricks year end show on NY day, but only 1 yr, and that yr was the Decade end chart, Top hits of the 90s special. They never aired a special on NY ever again, in fact, I never even heard a promo for the show on the station except for that ONE time. They buried the show on Sat am 5-9am during its entire run on the station, '97-'01. Now I also remember Star94 Atlanta doing Ricks Yr End on NY Day. I can only speculate that they probably aired it more than 1 yr but I can only confirm that they aired in 2004, or to be more exact, 1/1/05.
WKDD in Akron, OH aired the Dees Top 100 on a loop from 4pm New Years Eve thru the end of New Years Day in 2002 and 2003. In 2004 they added AT20, and would air the AT20 Top 60 and then the Dees Top 100 in full on New Years Eve and Day. That practice ended in 2006 when they switched to AT40 HAC and then later dropped Dees.
At the old Kiss FM in Meadville PA, the two years I worked there, we would pre-empt the show on Christmas weekend (Christmas was on a Sunday the first year, Christmas Eve was the Sunday the second year) and that was the first half of the year end. At the time we had a 48 hours of commercial free Christmas that was a huge sponsorship deal for the station. (the 2nd year I did the voice tracks for it and was the host, which was cool!) We would then air the full six hours the following weekend from 6am-Noon and 6pm-Midnight (the show typically ran 9-Noon and 9-Midnight Sundays) and then it would replay again on New Years Day from 6am-Noon.