Eli5 why does leap year happens only every 4 years

Question

Google says that “On Earth, a sidereal day is almost exactly 23 hours and 56 minutes.” Meaning that every year we lose 4×365:60≈24h so one day of time. And leap year is supposed to compensate for that but it only happens every 4 years not every year. Can someone explain me why is that so?

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Answer 1

A year is 365 days…and a little bit more

366 days is just too many, over several years your dates start drifting away from your seasons.

Or more specifically the dates designated for the solstice and equinoxes are no longer accurate.

So we deal with it by “adding” one day to the year every four years. However, every 4 years is in fact too often. Over many years we start start drifting. So every century we don’t have a leap year.

It’s still approximate, but close enough.