You’ve heard of the 4-day week – but what about the 9-day week?

You may have heard of the four-day workweek – where employees only work four days out of the traditional five, but for the same pay and with the expectation of maintaining productivity levels.

A largely successful half year court hearing this working pattern has recently been completed in the UK. Businesses have noticed increased productivity and greater interest from potential employees, while workers say it has improved their quality of life.

But concerns remain about factors such as profit, additional pressure on workers from a heavier daily workload, and the need to be available for customers throughout standard working hours.

Sam Franklin, the CEO of technology company Otta, adds that shaving an entire day seemed like a big step, as it cuts work hours by 20%.

“As I went from effectively 100% of the time to 80% of the time, I felt like I was probably rocking the boat too much,” he told CNBC Make It.

So is there a middle ground? Enter the nine-day fortnight.

The nine-day fortnightly work pattern effectively means that out of 14 calendar days, nine are work days and five are days off. Employees get an extra day off every two weeks, often on a Friday.

Some companies ask their employees to work longer hours on the days they work to allow for the extra day off, others say it doesn’t matter to them as long as their performance remains consistent.

Otta is one of the many companies currently trying out this working pattern – with the view that if everything goes well, a switch to a four-day week might be an option.

“As a stepping stone, it felt like you weren’t trying nine days fourteen days?” Franklin says.

Many of the benefits are similar to those of the four-day workweek, according to the testers. These include productivity, employee satisfaction, a better work-life balance and improved well-being. Franklin also noted that the issue came up during the hiring process.

“It’s one of those things that everyone mentions. When they’re like, ‘Hey, why do you want to work at Otta?’ It’s ‘I read about it, I love the way you think, I’ve always wanted to do this.’”

Ben Branson-Gateley, CEO and co-founder of human resources software company Charlie HR, which also follows a nine-day workweek, says he’s noticed additional benefits compared to the four-day workweek.

“The reason I’m really for nine and not four is because Thursday doesn’t become the new Friday,” he says. Alternating four and five-day weeks also creates a better balance, Branson-Gateley has found.

“These four-day weeks can feel them very strongly, they can feel pretty intense,” he says. “I don’t like the idea of ​​doing that every week.”

Employees can switch between workstyles and adapt to the way they work based on the number of days in their workweek while enjoying improvements in their quality of life, explains Branson-Gateley.

Both Branson-Gateley and Franklin have seen their employees change the way they approach work as a result of the nine-day fortnight. Franklin encouraged his employees to question whether non-decision-making or relationship-building work meetings are really necessary, while Charlie HR instituted a (mostly) session-free Deep Work Wednesday.

Similar to the four-day week, however, the nine-day week does not suit every company and every employee. One of them is the London-based PR company Stand, explains founder Laura Oliphant.

“The benefits were obvious, I felt we were better supporting employees’ mental well-being, reducing stress and burnout and giving them time to unwind. And the team felt more productive. But there were some downsides,” she explains.

Not all employees saw the benefits, Oliphant says, and because customers needed to reach someone at the company every day, Stand had to set up a roster that gave different employees different days off.

“The rolling roster was time consuming and complex to develop, everyone was working on different schedules, [and] Teams were strained when the roster coincided with busy holiday periods,” says Oliphant.

Stand now follows a 4.5 day work pattern – on Fridays everyone logs off at 1pm except for one person per team who is on the lookout for important emails.

This fixed the problems the company found with the nine-day workweek, but the benefits remain. And Oliphant’s greatest lesson from that experience?

“A key learning for us is not being constrained by a flexible model that works for someone else. It’s important to find one that works for your business and your customers,” she says.