I have no idea why this is unless it could be inheritance patterns - but the long saeculum seems to be an Agricultural Age thing, and a lot of Latin America is basically still there for all the veneer of urbanization and industrialization.
By inheritance patterns I mean that if someone has to wait for his father to die before coming into power, the generational turnover might be slowed down. Has anybody looked at that?
On the other hand, take Renaissance England. From Bosworth Field in 1485, when Henry VII took the throne, to Spain's first attack on young Elizabeth in 1559, was 74 years and that is not startlingly long. (It just feels like it, considering how much upheaval and turmoil was stuffed into that 3/4 of a century.)
How to spot a shill, by John Michael Greer: "What you watch for is (a) a brand new commenter who (b) has nothing to say about the topic under discussion but (c) trots out a smoothly written opinion piece that (d) hits all the standard talking points currently being used by a specific political or corporate interest, while (e) avoiding any other points anyone else has made on that subject."
"If the shoe fits..." The Grey Badger.