Yes, I am speaking from experience, I work at a V50 law firm, billed 2000 last year, and didn't work "60-70 hours" every week. It is understood at many firms that associates will "overbill," and it is true as Mr. Galt said that the hours can be cut, but most partners are either to busy, or just flat out don't care to do it.
Remember, you aren't literally working 100% of the time on a client's matter in order to bill 100% of it. Nobody I know stops billing a client when they go to the bathroom, or take a 5 minute coffee break. You just bill it all together, after all, you could be thinking about the work when you are chilling on the toilet, right?
And trust me, I'm not the biggest loser at my firm, and I didn't burn out after a couple months, simply because of the fact that I don't freak out over 10-20 minutes/day of overbilling.
The biggest losers are those who do.
Oh, and one last thing...nobody takes an hour for lunch every single day at my firm...