Whenever I get an email from LinkedIn telling me about all the new jobs I could apply for, I usually click delete. But last week, desperate to put off filling in a long tax form, I started trawling through the site’s latest job openings, and discovered something disturbing. One of the most annoying fads to come out of Silicon Valley in the past few years — the unlimited vacation policy — has spread.

It does not seem that long ago that boundless time off was a novelty promised by the likes of Netflix, LinkedIn itself and Virgin’s Richard Branson, who said he got the idea from Netflix. Now it is being offered by law firms in London, loan companies in Latvia, recruiters in Berlin and electronics outfits in Taipei. “Work hard and take time off when you need it,” chirped a typical advert I spotted from Taiwan’s Tomofun, a company that makes a camera for watching housebound pets from your desk.

The contagion is no real surprise. It is hard to think of another work perk that promises so much and delivers so little — to workers. It is a different story for companies. A big firm that ditches fixed paid leave for open vacations can wipe millions of dollars worth of unused leave liabilities from its books that would otherwise be paid to departing employees. At the same time, it can safely offer bottomless holidays knowing most employees will never take them, especially in the US, the only major advanced economy in the world that does not guarantee workers paid vacation time.