Six Months Into the 4-Day Work Week

Korea's Joining the Experiment

Starting in the second half of 2025, the 4-day work week became noticeably more common at Korean IT companies. Kakao introduced an alternating 4-day week, and smaller IT companies started testing full 4-day schedules. Over 100 companies joined the Ministry of Employment and Labor's pilot program. Six months in, the data is starting to come out -- results are better than expected, but it's not a silver bullet.

By the Global Numbers, There's No Reason Not to Do It

The UK's 2022 large-scale experiment. 61 companies, 2,900 participants. Over six months, average revenue went up 1.4%, turnover dropped 57%. 92% said they'd keep it. Microsoft Japan saw a 40% productivity boost in 2019. Iceland ran a 2,500-person trial and found productivity maintained or improved.

Numbers alone make it look like a perfect system. Revenue up, turnover down, satisfaction up.

But Korea's a Different Story

Or so people say -- and looking at the Ministry's interim report, IT-sector productivity was maintained on average but varied wildly. Companies running their own products did well, while SI/outsourcing shops ran into trouble because of client schedule conflicts. When your client works 5 days a week and you're off on Fridays, there's a communication gap.

A friend of mine works at a startup that adopted the 4-day week, and the first two months were chaos. Work piled up on Thursdays since Friday was off, meetings didn't decrease, so actual focus time shrank. Overtime quietly crept up -- a 4-day week on paper but real working hours roughly equal to 5 days. The irony. (Apparently this is way more common than you'd think.)

The turning point came when they changed their meeting culture. No meetings over 30 minutes, more async communication, focused work during core hours. They switched from Slack to Notion docs and killed unnecessary status update meetings. These changes stacked up until the team could genuinely fit 5 days of work into 4.

It Actually Suits Developers Pretty Well

According to Cal Newport's research, developers get an average of just 2.1 hours of uninterrupted focused coding per day. Whether it's 5 days or 4, productive coding time is roughly 10 hours per week either way. The rest goes to meetings, emails, and Slack.

That's why cutting a workday doesn't tank productivity. In fact, the extra rest day boosted focus during the remaining 4 days. Burnout dropped noticeably too. Using Fridays to rest, study, or hack on personal projects meant showing up Monday recharged.

What's Still Unresolved

The biggest issue is whether to maintain salaries. Most success stories kept pay the same, but that's a real cost burden for companies. Performance measurement also needs to shift from hours worked to output, but a lot of Korean companies still haven't shaken the "longest butt-in-seat = hardest worker" mentality.

There's also data showing the 4-day week is a powerful recruiting weapon. Job application rates were reportedly 2x higher on average.

The 4-day work week isn't just taking a day off -- it's a project to redesign how work gets done entirely. Without the boring work of cutting meetings, expanding async communication, and eliminating unnecessary processes, just skipping Fridays will fail. How many organizations can actually pull off that redesign? I have my doubts.