I've been convinced for quite some time that the 60-80 hour work week thing is mostly fictitious bragging and a culture of workaholic bravado. I think people actually lie about how much they work to appear more important or more 'serious'.

In any case if you are doing knowledge or creative work and are working more than 40-50 hours a week (for longer than a short crunch time), you are burning a lot of hours but are probably not working efficiently.