Oh, here's another one:
Sometime in the late 90's a pioneer told me she had calculated that Armageddon would start no later than 2005. There was something in the old Aid book about how Cain had been born when Adam was 30 years old, or at least you could "back into" that age.
IIRC, I think the Aid book said that Cain must have been "about 100" when he killed Abel, and Seth was born to Adam at age 130 as a "replacement".
Thus, the pioneer's reasoning went, Adam had been alone in the garden of Eden for 30 years, then Eve came along, was tempted & sinned shortly after her creation, then soon after that Cain "must have" been born.
And, so, continuing on, the idea was that Jehovah's "rest day" was still somehow supposed to last exactly 6000 (or 7000 when you tack on the "1000 year reign") years. She still accepted that 1975 was the date for 6000 year's since Adam's creation, so 2005 would be the 6000th anniversary of Eve's creation - the last of Jehovah's "creative works".
I grant it was creative. It still used good ol' Freddy's chronology and "logic" that the "old system" had to last exactly 6000 years, and still fit conceivably within "one generation" of 1914, while also mitigating the failure of the "1975" prediction.
It was a pretty good "last gasp" for Fred's chronology and calculations - and, obviously, just like the 100+ years of failed expectation that preceded it, utterly wrong.