When I was a kid, there was this event on TV one time called Go Ape. I think it was all the films as a marathon. It's fairly common to do that sort of a thing now, but back when there were only five TV channels and they went off the air at midnight, it was a big deal.
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I was wrong, it wasn't on TV, it was at the theaters. The TV marathon was only the first three films. I found an article about it;
The spur for finally starting production of a TV show was in September 1973, when the CBS network bought the television broadcast rights to the first three Planet of the Apes films for $1 million and showed them in a row on prime time screens. The broadcast registered a 33.6 Nielsen rating and a 57 per cent share of the audience to capture the number one spot in the ratings race for that week, and the highest ratings in history for a sci-fi series up to that time. In response, CBS soon aired the movies again in its 'Friday Night Movie' slot, while 20th Century Fox began showing all five Apes films in back-to-back six-hour "Go Ape!" marathons in movie theatres in the first half of 1974.
