My direct supervisor once told me that we needed to be putting in 45-50 hour weeks, just to set a standard of what is expected. I remember thinking "what the heck? If you want me to work an extra 25% a week, we're going to need to increase my salary by 25% to match it."
Anyway - when the boss had her first baby, it was the best day of my work-time in that job. Suddenly she became more understanding to people needing some flexibility in their schedule, to not wanting to work crazy extra hours but actually wanting to spend some time in the evening and weekends with family. We laughed about it with her about 6-7 years later - after she'd had her 2nd child - and she looked at us like it had never occurred to her what she was like pre-parent versus after she became a parent.