I stumbled across a new blog today that's worth keeping an eye on called the HR Capitalist. The article that caught my attention was about the challenges associated with a four day work week, especially from the standpoint of managerial or knowledge workers and creativity or innovation.
The author's point in the article is that a four day work week assumes that work can be compartmentalized and that there's an "on/off" switch to much of the work we do. For knowledge workers, who aren't tied to machines or production facilities, the myth of a four day work week is especially profound. Time and ideas don't stop just because you get Friday off, and while jobs tied to machines or production lines or facility opening and closing may be able to box their work into four ten hour days or some other format, many of us don't have that luxury. The author is pointing out that ideas and creativity happen when and where they will happen, and can't be boxed in, nor can you reasonably expect to control when and where any knowledge work happens. It's not aligned to a specific machine - other than perhaps a PC - so knowledge work is not reliant, or even in cycle with a production mentality.
Additionally, there's a negative connotation for creativity, innovation and knowledge workers in a fixed four day week. If the other guys can get their work done in four ten hour days, why can't you? Why can't you schedule your thinking, your creativity, your insights into a mandated time frame? Of course no one intentionally develops a four day work week with this in mind, but one of the logical outcomes is to compare output and to expect the same output per 40 hour shift over four days for production oriented jobs as for knowledge oriented jobs. In case you've not noticed, there was a big case study into this concept (called France, literally the country) that imposed a 35 hour work week for everyone, but has since relaxed those expectations. This is not to say that knowledge work can't be done quickly or efficiently, but that comparing the inputs and outputs of knowledge work versus production oriented work is like comparing my ability to swim to a dolphin's. Yes, we can both swim, but we have very different capabilities, expectations and orientations about swimming.
Anyway, I'd recommend looking at the HR Capitalist blog, as a good source for business oriented HR conversation.