"Changing any of these will make the summer drift into the winter, or the night into the day, or whatever." Leap days, sure. Leap seconds - as the article poi

"Changing any of these will make the summer drift into the winter, or the night into the day, or whatever." Leap days, sure. Leap seconds - as the article points out, there have only been 27 so far since 1970. Less than a minute per century isn't much drift, and could be corrected in a bigger block later.