Leap seconds are not a human interface concept. Humans don't care. People who haven't thought very hard about this tend to believe humans care but they don't.
If humans cared the existing systems couldn't exist. For more than a century we've all lived with time "zones" which are thousands of seconds wide and we're not bothered by that. Many of us have civil time systems which shift twice per year by 3600 seconds for really no good reason, and while that's annoying it's barely worth a brief mention on TV news or in small talk. Leap seconds are 3600 times smaller and happen way less often, they're entirely negligible.
They existed because we thought we cared, and we actually don't care, and we thought it was pretty easy to do, and it actually wasn't very easy after all.
If humans cared the existing systems couldn't exist. For more than a century we've all lived with time "zones" which are thousands of seconds wide and we're not bothered by that. Many of us have civil time systems which shift twice per year by 3600 seconds for really no good reason, and while that's annoying it's barely worth a brief mention on TV news or in small talk. Leap seconds are 3600 times smaller and happen way less often, they're entirely negligible.
They existed because we thought we cared, and we actually don't care, and we thought it was pretty easy to do, and it actually wasn't very easy after all.