I agree with the questioning of 80-hour weeks. Another factor many omit is the personal time many of us take during the workday. For example, my air conditioner tune-up is next week. They gave me a 4-hour window from 2-6 pm. So I'll work from home. However, there will be an hour in that period where I'm letting them in the door, asking questions, signing the paperwork, and letting them out the door.
What about dentist and doctors appointments? Lunches that run a bit long? Picking up the dry cleaning? Talking to your CPA on the phone while at work? Calling the wife for 10 minutes once a week to discuss the fact that the carpet cleaners showed up and dropped something on the rug.
The list goes on and on. I have no issues taking some time from work during the work day...as I'm not measured by hours, but rather by the work I complete. For me, I'm physically "on the job" about 50-52 hours a week....but probably 6-7 hours a week is the above examples where I'm at personal appointments....so my workweek averages in the mid 40s.
I work for a global MegaCorp, so about twice a week I have conference calls at 9 pm with Singapore or China, or sometimes India. There are a lot of "give and take" situations like this...I work some at night, and take some time off during the day for personal appointments.
There have been short periods where I've worked 70+ hours during a week, usually around SEC reporting since I'm in Finance. But when I work until 10 pm on a Sunday night getting the SEC reports ready and submitted, then I sleep in on Monday morning and come in at noon.
At the end of the year, so long as I can look in the mirror and say I'm doing right by the company, I can sleep at night and feel good about my work.