@frameacloud the 11 year solar activity cycle, and the 11.86 year orbital period of jupiter comes to mind
also in astronomy, precession of the equinoxes is on a 25772 year cycle
astronomy is a good source for long-period predictable cycles
in addition to 17 year cicadas, there are also 11 and 13 year cicadas, and probably some of other primes too
you get a new credit/debit card every five years, when the old one expires
@frameacloud someone liked this and i looked at it again and thought "wow that's a really mundane thing to end on after talking about astronomy"