I was told that the average attorney at a large law firm is expected to generate around 1800 billable and 600 non-billable hours per year.
Their computer tracks and accounts for every task; we complain about documentation and billing, they complain about having to account for every minute of their day. So if they have to go use the restroom or get some coffee the counter stops.
However, if you are talking about the "big boys" with the surgeon or NFL player salaries, that would be around 3500 billable hours a year and 600 non-billable so 4,000 hours a year. So 80 hours a week at 50 weeks a year. Again, that is 4,000 hours actually doing something.
I have a friend at one of those firms who does appellate work. He said 100-110 hour weeks are not common, but they are not unusual, depending on if a big hearing is coming up.