Tenure track profs work 80 hours per week? Really? They work from 8AM to 8PM, 7 days per week (taking only a 15 minute break each day to eat)???

This doesn't seem likely, since they would be completely burned out after only a few months, and you would have diminishing returns after the first week. If you are really working 80 hour weeks then you are being incredibly foolish and wasting a lot of time being completely unproductive due to exhaustion.

But, of course, you don't really mean 80 hours, you were just exaggerating a bit to make your point. Fair enough, lets say profs are putting in (I'm assuming a proper research university where tenure track professors teach 3-4 classes at most) 12 hours lecturing each week, for 30 weeks per year. That's (at most) 360 hours of teaching, per year.

Lets say you spend 2 hours per week preparing for lectures (you should know this stuff already, but lets say you just need time to get organized). That's 60 hours, yearly.

Now, lets say you spend 4 hours every day working on research. Everybody probably would like to spend more, but some days you have to see friends or your wife/husband or kids or get your car fixed or whatever. That's 4 * 365, which is probably a huge overestimate for most people, but that's 1460 hours per year.

Now, as for writing grant proposals, or mentoring students, or whatever else, nobody believes you are spending any serious time (more than 5 hours a week) on that. I don't know how long you really spend on it, but I'm going to assume that you aren't writing more than 1 grant proposal per month, so I'm going to just say that I gave very optimistic and too-high estimates for everything else, so this will get rolled in as overhead.

So you're doing (drumroll) 360 + 60 + 1460 = 1880 hours of work per year, all but 420 of which is just thinking about the problems that interest you most.

If you work in industry, you are spending 220 * 9 = 1980 hours per year working on stuff that are not the things that most interest you, and almost none of it is blue-sky thinking of any kind.

Want fries with that?

Edit: With my really crazy overestimates on how tenure track profs spend time, averaged over a regular work schedule it is 42.72 hours per week, of which 9.5 is anything at all besides pure 'research'. Odd that, it's within .5 hours per week of my original guess, and I swear I didn't cook the numbers to come to that.