During my first few years in the Unix room (starting in 1988) there was what seemed
like a semiannual flurry of leap year corrections made to research unix.  Apparently, there
was some aspect that kept misbehaving, with new bugs appearing at the next shift in time.

I never bothered to investigate the specifics, but it happened over several years.  There are
probably some on this list who know more details.

I don’t recall this being a problem on Plan 9.

ches