I used to think the hardest thing about career development was working out what you want: once you have some realistic ambitions, achieving them is relatively easy. But it turns out there is something harder: mastering the art of earning more, while working less. It is an almost impossible trick to pull off, unless you are a NHS consultant, or unless, as I learnt this week, you are the entrepreneur Timothy Ferriss.

The 29-year-old American, who runs BrainQuicken, a sports nutrition company, says he has gone from earning $40,000 (£19,400) a year, working 80 hours a week, to earning $40,000 a month by working just four hours a week. Now, presumably with all the spare time he has on his hands, he has written a US bestseller, The 4-Hour Workweek: Escape 9-5, Live Anywhere, and Join the New Rich, to teach us how to replicate his success.

Given that time is (not enough) money, a synopsis is probably in order. Apparently, it all started when Mr Ferriss realised that, out of more than 120 of his wholesale customers, just five were bringing in 95 per cent of revenue. Facing burn-out, he decided to alter radically his working life to reflect this reality. He gave up chasing the unproductive majority of his customers entirely to concentrate on the biggest. He switched to “a low-information diet” – never reading or watching the news, instead picking up titbits ambiently. And he stopped taking phone calls, letting all calls go to voicemail and picking up messages occasionally.

Meetings also went, unless they were for making decisions, in which case he gave them a maximum time of 30 minutes. And to avoid wasting time sifting through email, he allocated just one hour a week to the task of checking his inbox. Not that it was very full – he hired personal assistants in India to manage his messages and gave permission to his customer service supervisors to resolve anything that took less than $100 to fix without contacting him.

Thanks to such extreme measures, Mr Ferriss says he shrank his working week to almost nothing and has since used the spare time to set a world record in tango, learn to surf and, of course, write a book to spread his message. Should we listen?

On the face of it, Mr Ferriss’s ideas are ingenious – one is to ward off unwanted visitors to your cubicle by wearing headphones which are not plugged in. We Brits have long known that a lot of what we do at work is not useful – our output per hour is famously lower than that of Germany, the United States and France – and barely a week passes without someone somewhere publishing a survey exposing the ways in which workers everywhere waste time.

In the process of trying to find an example, I came across no less than 28 such reports printed in recent years alone. “Increasing stress in the workplace is costing British firms £1.24 billion a year, according to a report from Personnel Today magazine.” “The average British workplace wastes more than an hour a day on office politics, resulting in lost productivity costs of £7.8 billion a year, according to reed.co.uk.” “Spam costs American companies more than $70 billion a year in lost worker productivity, according to a study released by Nucleus Research.” And so on.

However, such generalisations about “lost productivity” rarely survive close inspection. Take the survey revealing that America loses $70 billion a year to spam, for example. The figure is based on an estimate that the average internet user spends 16 seconds looking at each junk email before deleting it. Does it really take that long to register the phrase “cheap Viagra”? Don’t antispam filters get rid of most spam anyway? Could it be that such surveys are actually spurious attempts by PR consultants to get the names of obscure clients into the papers?

Indeed, as many managers have found, to their frustration, productivity is not a simple business. Leaving aside the question of how you measure such things, many of the things that are said to reduce productivity also boost it. Take stress for example. It does lead to people getting ill and taking time off. But it also propels productivity – if I did not have the stress of the occasional deadline, I would achieve less than I already do. And Lord knows how you create a workplace without office politics. Where you have people, you have politics, and while some of it is enervating, some of it is also necessary.

Which brings me back to Mr Ferriss and his central idea that we can save time by minimising contact with human beings. He is right to conclude that most interpersonal contact in offices is aimless. But it is also crucial to business in that it often leads to new and unexpected ideas. It may be a banal example, but if I had not been discussing I'm a Celebrity Get Me Out of Here with a colleague last Friday afternoon, I would never have spotted, on her desk, the American magazine in which I read about Timothy Ferriss, and this column would not have happened.

It seems to me that most of Mr Ferriss’s ideas only really work if you run your own online business. You would not last long as a doctor if you went around with a pair of headphones permanently plonked over your ears. Some meetings actually need to last more than half an hour - I hope the MPC takes a little longer than that when setting interest rates. And if the average worker started checking email just once a week, I cannot help thinking that one of the messages they eventually received would feature the subject line: “Fired”.

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