Is unlimited vacation too much of a good thing? A number of tech firms—including Netflix, Zynga, and Evernote—have stopped restricting their employees to a set number of paid vacation days per year. The catch, of course, is that employees must continue to fulfill all their duties. Despite the tantalizing prospect of dropping everything and heading off to a tropical vacation for a month (or even sitting at home, binge-watching the next season of “Daredevil”), the vast majority of employees with unlimited vacation time don’t take very much of it. When one small startup instituted such a policy, for example, it found that employees took roughly the same number of days off as when they had a more regulated PTO system. After lots of buzzy headlines about unlimited vacation, some tech companies are even beginning to rethink their approach. In September 2015, Kickstarter dropped its unlimited vacation policy, claiming that employees found it too confusing. Instead, workers receive 25 paid days off per year. “What we found was that by setting specific parameters around the number of days, there was no question about how much time was appropriate to take from work to engage in personal, creative, and family activities,” a Kickstarter spokesperson told BuzzFeed News at the time. So few people were taking vacations at Evernote that the company now pays employees a cool $1,000 to take a certain amount of time off every year. No matter how much unlimited vacation is meant as a morale booster, many employees are probably afraid that taking too much time off will negatively affect their career, and end up taking as many vacation days (if not less) as they did before. Tech employees tend to be driven and highly motivated, often working on multiple projects simultaneously—they don’t want the various threads of their professional lives to drop for very long. If you work for a company with unlimited vacation, and find yourself confused about how many days to take off, ask your co-workers—or even HR—if there’s an ‘average’ length of time. If you use that number as a starting point, you’ll probably feel more secure about actually taking days off. And you should take them, because burnout is no laughing matter.