The average work week in US is 43 hours. To be precise, it is on average 8.6 hours per day worked.
Working 11-12 hours is definitely not common. Of the few people I know who do it, all do it voluntarily.
People consistently overestimate the number of hours they work, particularly if they work more than 40.
Source: http://www.bls.gov/opub/mlr/2011/06/art3full.pdf