As I mentioned before, I don’t think you should work anywhere close to 40 hours a week. Thinking about work in hours is wrong.
A standard work contract contains a fixed number of hours an employee has to be working for the company. What does that say? That the working hours are more important than the actual achievements? I’ve met many people who “sat it out” one time or another, stayed in office simply to fulfil this fundamentally flawed contract.
In that common scenario, it is in the interest of the company to make employees more efficient, but not in the interest of the employees, because they’d get stressed out by a 40 hour week crammed with work.
What if it were the other way round? If contracts were based on achievements, not on hours? Now employees want to be more efficient, so they can leave work earlier. They even want to be more effective, because that’s what’s getting them paid — and as a bonus, it’s also what’s moving the company forward.