In most cases, if you give your employer a little more, they will give you a little more.
I have worked places that expected a 55 hour week for salary. I amnow at a really good company that makes a much higher margin, and they LOVE when guys really work hard and put in 45 hours a week. Some of the kids I have come through as intern have NO CLUE how good they have it here, and think going somewhere else for another $3,000 a year is smart.
Those are the good kind of companies, the ones that appreciate extra hours or effort. I'm more of an extra effort than hours guy, I'd rather work at top speed for 8 hours than work 10 minutes of OT. Of course I'm also a natural born multitasker, so if I kick it into gear I can get two or three days work done in one day.
The companies that expect long hours are also the ones that will never reward the extra effort. It's not in their best interest. They know that every time they convince 2 employees to work 60 hours instead of 40 they just got an extra full time employee for free, and why would they want to promote an employee that's going to require 1 1/2 hires to back fill his old position. Companies like that frequently don't back fill, that's the sure sign of pure user company, anybody that gives promotions without backfill (thus now expecting the person to do two jobs for the price of one) should be resigned ASAP.