As summer winds down, the concept of “unlimited vacation” sounds pretty good. OK, it sounds pretty good regardless of the season.

But unlimited vacation is an actual thing: a policy by which employees take paid time off when they want or need to. You don’t start with an allotment of days for the year. Any day is a potential day off. The deal: in return for this kind of flexibility, you make sure your work gets done in timely and satisfactory fashion.

Jennifer Blackburn, senior account manager at the Atlanta public relations agency ARPR, has had three weeklong vacations within the past nine months: to Paris, Cancun and Florida. Her company, she said, encouraged her to enjoy all of her vacation time and not worry about the work she was leaving behind.

“We’re really supportive of each other,” Blackburn, 27, said. “The more freedom and flexibility we have, the more productive we’ll be because we feel more valued.”

Unlimited vacation can have a strong effect on a work environment.

“The policy sends a signal to other people in the labor market that ‘we are employee-friendly to your life and to your work,’” said Wayne Cascio, a business professor at the University of Colorado. “To the extent companies can afford these policies, that’s what they’re going to do.”

‘It is left up to the employee alone’

Since 2004, Netflix has had a "no vacation policy" — meaning the company has no allotted vacation time and allows employees to take off as they see fit. Earlier this month, Netflix announced it would start offering one year's paid leave for new parents. GE started its new unlimited vacation policy this year.

Richard Branson of Virgin put it this way when he enacted an unlimited vacation policy last fall:

The policy-that-isn't permits all salaried staff to take off whenever they want for as long as they want. There is no need to ask for prior approval and neither the employees themselves nor their managers are asked or expected to keep track of their days away from the office. It is left to the employee alone to decide if and when he or she feels like taking a few hours, a day, a week or a month off, the assumption being that they are only going to do it when they feel a hundred percent comfortable that they and their team are up to date on every project and that their absence will not in any way damage the business – or, for that matter, their careers!

Cameron Conaway, a content marketing manager in Philadelphia, remembers watching his mom clock in and out of work when he was growing up. Conaway, 30, doesn’t see the need to be in an office to get his work done.

“It’s an antiquated model for the modern workplace,” said Conaway, who works for the task-managing application Flow. “I love my work so much that when I get an idea for a blog post, I’m going to leave the beach and go write it down.”

‘There’s still some type of stigma’

In a recent survey of advertising and marketing executives and office workers, nearly 40 percent said productivity would increase if their employees had this policy. The study, by The Creative Group staffing firm, included more than 400 executives’ responses, as well as those of 430 office workers.

Interestingly, 60 percent of workers in the survey said that, if given unlimited vacation, they’d take off about the same amount of time as they do now. Even with unlimited vacation, some employees avoid taking time off because they don’t want to be seen as slacking or, perhaps more important, as taking more time off than coworkers.

Ethan Austin, cofounder of the medical fundraising startup GiveForward in Chicago, didn’t want his employees to feel that way. That’s why Austin’s company changed its policy: it already had unlimited vacation, but now it requires employees to take a minimum of 15 days off a year.

“We found out that even if you have a policy, there’s still some type of stigma felt,” Austin, 34, said. “Everyone feels the pressure to perform well.”

‘Those who abuse it don’t last long’

Most employees don’t abuse unlimited vacation policies, said Cascio, the Colorado business professor, but those who do often wind up quitting.

“It really depends on peer pressure,” he said. “For those who do abuse it, they don’t last long because they don’t like feeling ostracized.”

Brian Easter, co-founder of the Atlanta-based digital marketing agency Nebo, said workers shouldn’t be motivated by fear to do their jobs well.

“We are trusting our employees to make good choices in their lives and their work,” said Easter, 40. “Let’s be adults and allow them to better live their lives.”