So, today is 29 February. A lot of people have been arguing for a day's holiday today, on the grounds that they are providing a day of unpaid work for their employer. And some organisations are even going along with this, on somewhat pious grounds of "saving the environment". Of course, these employers cannot know if they are saving the environment or not, because they don't know what their employees are going to do on their day off. For example they could charter a private jet and take a round trip to a distant country (especially this year, when 29 February conveniently falls on a Friday).
Be that as it may, I don't agree with the premise that one works "for free" on 29 February, as the "day" is an artificial unit created by us. It does not properly fit reality (the natural world), hence the need for the four-yearly correction. An employee could just as easily think of it as receiving an extra quarter of a day's pay for nothing every three years, in preparation for the fourth year when she or he works the "extra" day.