I was in a Graphics lecture at university a couple of decades ago when the lecturer (who always wore two ties at once - nobody found out why) wrote on two and a half boards an equation for calculating the intensity of light at a particular point. He said it was very accurate. He then wrote an equation with less than 10 variables and operators combined. He said that the latter was an approximation of the former and was deemed "close enough" for most uses including commercial use. He said that this is what he called "efficient laziness" and he thoroughly encouraged us, both in academia and in our forthcoming careers, to apply "efficient laziness" wherever possible. He also said that if anyone was too lazy to do their work then he had no time for them so we weren't to come to him with excuses.

Great advice.

Not sure about his ties though. My theory was that long before he had accepted a bet that he had to wear two ties until someone asked him why he did it...and no one ever did.