Megan McArdle is a Bloomberg View columnist. She wrote for the Daily Beast, Newsweek, the Atlantic and the Economist and founded the blog Asymmetrical Information. She is the author of "“The Up Side of Down: Why Failing Well Is the Key to Success.” Read more opinion SHARE THIS ARTICLE Share Tweet Post Email

Photographer: CARL COURT/AFP/Getty Images Photographer: CARL COURT/AFP/Getty Images

Today Bloomberg reports that Grant Thornton, the nation’s sixth-largest accounting firm, is planning to offer unlimited vacation days, a perk that is available at less than 1 percent of American firms. The idea seems to be to emphasize a culture of personal responsibility -- and perhaps to lure some good workers away from larger competitors.

But how much of a perk is this, really? There’s a reason that you tend to see this perk at places like Netflix, rather than places like Wal-Mart: they’re staffed with workaholics who probably don’t take much of their vacation anyway.

A few years back, I interviewed ethnographer Kathryn Edin, who described the rise of what you might call “supermarriages” among the educated classes: equal partnerships among people with a lot of status, a decent amount of income, and a lot of shared interests. These relationships produce very high levels of satisfaction and stability, higher than people used to enjoy, even as relationships among those without college diplomas are more frail and unsatisfying than they were before.

That same class of people often enjoys what you might call “superjobs”: careers that offer a lot of intangible rewards in terms of status, intellectual stimulation, and personal fulfillment along with some decent monetary remuneration. The people who do these jobs have a very high level of commitment to their work, partly because the people who do them tend to be hard-working, and partly because being a successful professional is such a deep part of their personal identity and ethos.

Superjobs are arguably the reason for a startling recent phenomenon: for the first time in history, the wealthy have less leisure than the poor. If your company mostly provides superjobs, it’s safe to give people any number of vacation days, because they probably won’t take them anyway.

As the lucky holder of one of those superjobs, I have exactly this experience. Since graduating from business school, I have worked for companies that offered two to five weeks of annual vacation, and I have never once managed to voluntarily schedule the allotted amount. I like my job, so I don’t spend a lot of time dreaming about getting away from it. But there’s also the structure of superjobs. People who hold them are rarely interchangeable with others; leaving for a week or two means leaving things undone until you get back. The world will not, of course, spin off its axis if I leave one presidential campaign's policy paper uncommented upon. But people in superjobs tend to lose that perspective.

Superjobs also come with supermetrics for performance. No one monitors how many sick days you take, or how often you’re out of the office, because they don’t have to. The driven people who do these jobs know very well that the things they are responsible for -- whether they’re project deliverables or client satisfaction -- directly depend on how many hours they put in. This is far more effective motivation to work than the beady eye of a supervisor.

There is, however, one company that managed to get me to take all of my vacation: the Economist. It had a serious mandatory vacation policy. We got five weeks of vacation, and taking it was mandatory. Really mandatory: Every year I was required to take most of December off when it was discovered that I had once again failed to take enough vacation in the previous 11 months.

If superemployers are serious about giving vacation as a perk, that’s the kind of policy that actually matters: not a theoretical gift of unlimited vacation days, but a policy that ensures that you can actually take them without feeling like a slacker. Otherwise, it’s a “free perk” that’s worth exactly what you pay for it.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.