If we wanted to produce as much as Keynes's countrymen did in the 1930s, we wouldn't need everyone to work even 15 hours per week. If you adjust for increases in labour productivity, it could be done in seven or eight hours, 10 in Japan (see graph below). These increases in productivity come from a century of automation and technological advances: allowing us to produce more stuff with less labour. In this sense, modern developed countries have way overshot Keynes prediction - we need to work only half the hours he predicted to match his lifestyle.

The progress over the past 90 years is not only apparent when considering workplace efficiency, but also when taking into account how much leisure time we enjoy. First consider retirement: a deal with yourself to work hard while you're young and enjoy leisure time when you're older. In 1930, most people never reached retirement age, simply labouring until they died. Today, people live well past retirement, living a third of their life work-free. If you take the work we do while we're young and spread it across a total adult lifetime, it works out to less than 25 hours per week. There's a second factor that boosts the amount of leisure time we enjoy: a reduction in housework. The ubiquity of washing machines, vacuum cleaners and microwave ovens means that the average US household does almost 30 hours less housework per week than in the 1930s. This 30 hours isn't all converted into pure leisure. Indeed, some of it has been converted into regular work, as more women - who shoulder the major share of unpaid domestic labour - have moved into the paid labour force. The important thing is that, thanks to progress in productivity and efficiency, we all have more control over how we spend our time.