The one thing that I disliked about my first job was how they pushed the idea of it being a 40-hour work week -- salaried of course. However, you go there, and then they drop the usual bomb, "we'd like you to at least work an extra 10%". Throughout my first year, I worked the hours that I needed to (at least 40, of course). I think my longest work week was about 55-60 hours when I was put on third shift due to lack of available SIL (System Integration Lab) time. What was the comment? "Well, you only averaged about 42 hours per week" "Yes, because I usually could finish my work well within 40 hours." "Then go help someone else."
My thought? "Okay, so you want me to take up a coworker's time for him to delegate some of his work to me?" If my team leader thought that another group within our team needed my help, then he would've asked me to help them, and I would've gladly done it. In other words, it wasn't needed and it takes up time on my side and the other group's side just to set everything up and potentially teach me the things I need to know to do the job.
The biggest thing about it that bugs me? That was a defense sector job, and why does a defense company want me to work more hours? That's because I don't get paid for it, but they do. The hours get charged to the contract, which is money in their pocket. At my current job, I get comp time for any hours over 40. If I don't use it by the end of the year, it gets paid out at 100% normal hourly rate.