Surprising? To whom, exactly? The 40 hour work week was created and optimized for a world in which the dominant work was repetitive physical labor. They determined at that time that around 40 hours was optimal for average peoples capacity for that type of work. That type of work has been greatly reduced, and been replaced with mental work. Human beings have radically different capacities for mental exertion compared to prolonged physical exertion.

Most businesses are run in a very 'cargo cult' manner, where the managers and executives still read books written by manufacturing magnates and then turn around and apply the same practices (or close facsimiles like tribespeople crafting 'headphones' with coconut halves) to their own companies. There is vanishingly little actual thought that goes into it, or consideration of the constraints and principles. Manufacturers found it beneficial to makes as much of their process routine and checklist-driven as possible, so modern companies blindly try to do that too. They don't realize that with mental work (whether something like software development, marketing, sales or art creation or much else that now dominates) this is actively destructive. No one pays a company to do simple checklist-driven routine thinking for them. When it comes to mental work, customers want novel solutions to problems. They want something that hasn't been done before. Every time. If you do manage to reduce your product to the outcome of a checklist performed by disposable workers... you've successfully destroyed the entire value of your product.

When a company is built, they hire workers. Workers are human. This places restrictions on the company. They have to install bathroom facilities. They have to offer breaks for lunch. These aren't just legal requirements, they're necessary to get good performance out of human workers. Being annoyed with the restrictions born in human nature and seeking to squeeze workers at those points is counter-productive. And humans have limitations to their mental capacity as well. These aren't rigidly defined and understood yet, and there will certainly be further development of our understanding as we go on, but we do know a good bit already. Extended periods of mental exertion are counter-productive. Given the cost of poor performance in most mental work, it would be wise to guard against this. Humans can not multitask mentally, as our brains facilities for attention simply do not permit it. Mental work suffers in environments where people are subjected to interruptions, and where they are continuously concerned with preserving social status and similar factors.

Socially we have a long history with notions of endurance and vigorous exertion being identified with virtue. That was very socially useful when dealing with physical labor. It is, however, very destructive when dealing with mental labor. Likewise, extroversion was very socially useful when dealing with collaborative physical labor projects, while introversion is far more useful when dealing with mental labor projects because significant portions simply can not be collaborative. (A systems design might well be collaboratively created, but once decomposed into manageable portions it becomes counter-productive to pile many people on a single manageable portion. They end up spending most of their time trying to synchronize everyones mental model of the same thing.)

What would surprise me is if experiments like the one described in this article actually resulted in any significant change to most companies. We literally have over 1,000 studies establishing the productivity-destroying nature of open floor plan offices, for instance, but they continue being used. Different excuses are always proffered (reduced expense, some people wrongly guess it would make them more productive in defiance of all research, etc) but they never compensate for the costs. In reality most of it is done because 'everyone else is doing it' or 'this is how its been done before.' So, research is great but implementing it is an entirely different story. Few are courageous enough to defy social convention and stick their neck out trying something new that is not intuitively obvious (from an intuition developed out of a manufacturing-driven working world).