Sometime between (say) 1974 and 1978 I read a story in a children's magazine (possibly one that also serialized the cartoon "The Adventures of Tintin") about a society where each year everyone had to leap across a gorge to make it into the new year. If I recall correctly, it was explicitly a supernatural thing - if you didn't jump you died automatically, and no one seemed concerned about the possibility of dying at any other time). This answer mentions that story, so at least I'm not the only one who remembers it. If I recall correctly the magazine that published this story published other SF, and also serialized stories that were too long for one issue.
