Jason James at We Are Mamoth writes about the culture of working long hours, and what those 45 hour weeks really mean. His first point goes straight to the money:
If you’re salaried, you’re working for free. After 40 hours a week, every hour you work adds $0 additional dollars into your pocket.
But I think it’s better (or worse) to look at it this way – you’re still getting paid for your hours, but £500 a week for your contracted 35 hours values your time at £14.30 an hour, but a 45 hour week values you at only £11.10 an hour.
He makes many other points, read more at “What Long Hours Really Mean”