I think there are two large flaws in your thinking that your number of hours in the office correlate directly with "more work experience".
1. There is so much more to "work experience" than the hours you spend in the office.
2. Most applicants spend more than the average 40 hour work week in the office.
I would say the average applicant works significantly more than the average 40 hour work week. In fact, I don't know anyone that works less than 60 hours a week that has now chosen to apply to Bschool.
That being said, Bschools aren't necessarily looking for someone that has worked 6000 hours or 10,000 hours, or 2000 hours. The average american full-time work week is 2000 hours, yes, but there is so much more that a Bschool cares about, none of which have to do with the amount of hours you've spent as a spreadsheet monkey. And how many "average" Americans do you know applying to top Bschools?
As banker, I know that there is a lot to learn from 1000s of hours of "working". But there is so much more to learn in the years of work experience; Performance evaluations, promotions, time management, life/work balance, office culture, interworkings of a business/company, new positions, new initiatives, new bosses/coworkers, new teams, etc... All of this learning moves at the same pace. Bschools want you to be able to apply this knowledge to what you're learning. I'd even argue that most schools would care just as much, or MORE about some of these topics than how many hours a week you work.
It's the same old story. Guy works for 1.5 years, works long hours, and suddenly thinks he has 5 years of work experience under his belt. This isn't how it works. Adcoms know industries and typical hours, but they want to see that you've had enough time to grow personally and professionally...
If you need further proof about the "average" 40 hour work week for bschool applicants I would take a look at this poll:
how-many-hours-do-you-work-a-week-126914.html It hasn't filled out yet, but I'm confident that the 40 hour work week idea will go out the door...