Friday we will be saying good-bye to holiday-ridden April with … yet another public holiday, the worldwide celebration of the improvement in the socio-economic conditions of workers. But were does this holiday come from?

Labour Day has its origin in the British Eight-hour day movement, led by Robert Owen from 1817 for several decades. Its slogan, “Eight hours labour, eight hours recreation, eight hours rest”, illustrates the goals of the movement perfectly. At the time, the working day lasted between 10 and 16 hours, 6 days a week. Despite Owen’s toiling, most countries had to wait until the early and mid twentieth century for a work day to be legally limited to eight hours.

Not all developed countries enjoy this work hour protection, though. And some bend the rules in pursuit of more time at the office. The Japanese, for example, are notoriously bad at sticking to their 360 hours per year restriction on overtime (about two hours per work day). Furoshiki or ‘cloaked overtime’ – workers staying at the office with the lights off or taking work home – is widely prevalent. It’s no accident that the Japanese language has a word specifically for death from overwork: karōshi. In 2007 there were 147 karōshi deaths and 208 cases of severe illness due to work-related stress.

This would explain the market in Japan for the i-pot. In this work-focused culture there is often no-one to regularly check in on elderly parents. But no worries, this kettle sends a signal through to a relative’s laptop, monitoring whether the elder is still alive and well and switching on the kettle regularly.

While working long hours is common among cultures that associate hard work with a good and meaningful life (look no further than the Afrikaner’s Calvinist work ethic locally), fear of losing your job can also be a big driver of working longer hours than necessary. But the reality is that, for most people, the law of diminishing returns kicks in after about 7-8 hours of work per day. In other words, at some point the extra hours start to add very little extra productivity. In fact, excessive overtime could even cause you to revise and destroy some of your good work due to fatigue and the poor judgement that often accompanies it.

Work-related burnout is a very real threat, with people in the ‘caring professions’ being particularly susceptible, according to Christina Maslach in Burnout: The Cost of Caring. In worst-case scenarios, burnout could lead to contempt for your clients and ultimately total abandonment of your career.

‘A 40-hour work week? Forget it!’ says Tim Ferriss on the other end of the work-life scale from karōshi. How about the 4-hour work week? Ferriss propagates the new rich lifestyle – valuing time as your greatest resource, in order to pursue the adventure called life.

I can appreciate Ferriss’s philosophy. While regulated work hours are necessary to protect repetitive task or support service workers from employer exploitation, a fixed number of hours per week for anybody else doesn’t really make sense. There are just too many other variables driving productivity: intelligence, experience, creativity, inspiration, peer-appraisal, physical fitness, EQ and biorhythms – to name only a few. Hours at work seem a very poor indicator of value added. And we haven’t even brought human capacity to create value-adding systems and ultimately earn a passive income into the equation yet.

But while we’re given the choice to either take a break or not on Friday, let’s celebrate!