Most of the testers available on
the market today test for this. The theory is that, since only one in four
centuries are leap years, there may be some RTC's which are not aware of this.
(Indeed, they may be using an inaccurate algorithm to calculate the instances
of leap years). Although we do not expect to see many PC's fail this test,
again it would be folly to assume that there is no need for it.