A guide to Jack Dorsey's 80-hour workweek
money.cnn.com
money.cnn.com
Also after working 40 hour weeks for some time I think you really need a weekend to get some stuff done at home and all the personal correspondence. Also you really should relax some time, otherwise you burn out faster then a tea candle.
I don't recommend it to others, but I do enjoy it and the fruits thereof (creative, moreso than monetary). I also maintain an active social life and a healthy long-term relationship. Both of which are born of a solid understanding of my strange schedule from those close to me.
I also work from home 90% of the time, which makes it far more manageable. I wouldn't want to attempt my schedule with a commute involved, but I don't doubt it's possible for others.
If you have a passion for your work, and no life outside of work... sure, it could be done. Not that I have any desire to try it.
Edit--my spelling is rather shakey.
Note in this case, Dorsey is working for two different companies, and in at least one of them he's a founding executive. Even in the EU, a founding executive might not be covered by work hour restrictions that apply to his employees.