The 80-hour week would be 11.4 hours, seven days a week. I have a hard time thinking most academics I know, those with spouses and friends, children, needs for sleep and sustenance, and blogs, are putting in those kind of hours. That would leave no time for Bildung or working on the scholarly base. Or Drinking. That would be everyday, working from 8-4 in the office, and then maybe working at home from 6:30-11 after dinner. Seven days a week, not just M-F. Not even my workaholic ex-spouse did that.
It's not real: people I know are not doing this. To figure out how many hours you are working, follow yourself around for a week and keep track. I've done that. Click on a link and you'll see an example of a 13 hour day I put in once. That's not typical though.
It's not necessary or desirable: there is no way that you can do intellectual work at a high quality this many hours a day.
It is not efficient. If you are doing this you are doing unnecessary things, or doing relatively trivial tasks the hard way.
Chances are, if you at a teaching intensive position, you are busy most of the time, but you aren't publishing or three articles a year.
If you are at a research intensive place, you are teaching two courses and publishing an average of 1.5 articles a year. You'll have one book for tenure, another one for full professor, and maybe an edited collection or two along the way.
I firmly believe you should occasionally coast. I have published four books, but there have been months I didn't work at all on writing books and articles. Even two month stretches. Yes, I could have eked out even more publications than I have, but to what end? I might only have six books in me for my career and I would be happy with that.
Academic hours will be variable. The 80 hour number cannot be an average; maybe it is an upper end.