The Times of London has an article asking, “Will law firms embrace the four-day week?”

Of course, as I’ve written about previously, there are firms that have already embraced a 4-day week, like Kromann Reumert and Molt Wengel in Denmark. But by “law firms” the article really means London law firms, and in particular the Magic Circle— the biggest and most profitable of the city’s firms.

However, people are skeptical:

Tony Williams, director of Jomati, a legal profession consultancy, says that it would require “major changes” regarding earnings expectations, billing methods and working practices….

Suzanna Eames, chairwoman of the junior lawyers division of the Law Society, says that it could help address the “endemic problem with burnout” in the legal profession. But shortening the week, she says, would at present mean working longer hours in fewer days to reach the same target of billable hours. For the concept to work, she says, “there needs to be a wholesale reform of the billable hours charging model — which appears to be a long way off yet”.

It’s absolutely the case that billable hours is a gigantic cultural impediment to the 4-day week in the legal profession, and that it’s easier to imagine (I talk about other professional service firms doing this in my book SHORTER.) However, there are other factors that weigh in favor of a 4-day week even at firms that don’t first move to project-based billing.

The experience of Canadian firm YLaw is particularly illustrative. They implemented a 4-day week last year, and started measuring the results a month in. Let’s look in particular at billing and net profits.

Founder Leena Yousefi had been willing to take a 5% hit to billing, but instead, “lawyers billed an average of 13% more working 4 days a week versus 5 days a week,” because they were more focused and productive, motivated to make a 4-day week work, and better-rested after a 3-day weekend.

Second, “net profits grew by 12% working 4 days instead of 5 days a week! I was expecting profits to go down by 5% to 10% but the reverse happened.”

And of course, people were happier, better-rested, had more time for family, etc.

There’s another important source of gains for these firms: lower unwanted turnover. Of course, most law firms are built with the idea that even when times are good, some people are going to leave, and not everyone is going to make partner; but there’s a big difference between losing that associate who decides to go in-house, and a partner who’s your expert in EU regulations around the valuation of intellectual property and intangibles, who works closely with two of your biggest clients, and who would be really hard to replace.

Losing that person can mean pissed-off clients, a drop in your service level, and all the costs associated with having to hire one of the other 14 people in the universe who can do that work— not to mention the irrepressible loss of all the informal knowledge about the client and their issues.

So the benefits of higher retention are nontrivial for firms: it can mean fewer interruptions in service (and no loss of billable hours for the months when someone has left and hasn’t been replaced), better quality of service to clients, and lower costs associated with recruitment.