A few days ago I met a friend of mine who works for an investment bank - a very famous investment bank -so much in fact, that it's odds on their name will probably morph into a synonym for investment banks, as in the way hoover represents vacuum cleaners, and Google, Internet search engines.

Though for many people, it's a the thinnest of thin line between saying this particular employer is famous or indeed infamous. Such is the temper of the times.

My friend works very long hours. It's a City thing. Bank the hours up. Dawn past dusk, five days a week, and on the weekend, log on at the kitchen table or scroll the Blackberry waiting in the Sainsbury's checkout.

I've never understood the cult of long hours. It must be the most in your face example of the law of diminishing returns; after a certain point, there's nothing left to give. The freshness has all gone. It's simply not an efficient use of resources or intellectual capital. What happened to the notion of "sleep on it"? Where are those wonderful, unexpected eureka moments going to come from?

Long hours is the sworn enemy of creativity. There's a tipping point when the juice of enthusiasm just pours away and there's nothing left but weariness and dejection at the thought of more fruitless hours to come, and that other silent assassin of thoughtful, stimulating work - frustration - making it's baleful appearance. Frustration almost guarantees recklessness - we're so tired, so stale, let's try anything.

Cult worship has other idols than simply long hours. There's the act of appearing busy. Not the actuality of doing something, this is instead, the dust-storm of seemingly being busy, with nothing happening.

I am reminded of the antonym of mere busyness, which is a combination of peace, reflection, and observation, and how that serves us far better than whirling around frantically, by these words of Viscount Grey of "The lights are going out all over Europe" fame: If we sit down in some secluded spot, unobtrusive and still, we shall presently understand how much there is that as passers by we never see".