Some jobs don't "require" more than 40, but when your fellow developers are always there earlier and later than you are, and when your performance reviews go from bad to good after you ratchet up your number of working hours, and when your assignment list keeps growing longer and more urgent, you get the message.
This is probably a sign to change your situation. Start working 40 hours a week, expect bad reviews short term, build a huge open source portfolio using the extra 10-20 hours/wk you've created for yourself by opting out of the sick system.