You sure? I know that (for practical reasons?) my contract states that I have to work 40h/week as an employee. But in reality I do not spend such time working,

You sure? I know that (for practical reasons?) my contract states that I have to work 40h/week as an employee. But in reality I do not spend such time working, I do work less. How much do I work? Whatever amount of time is needed to accomplish my team's goals, and in any case not more than 40h/week. I think it's somehow implicit that (especially) knowledge workers do not work counting the hours of work, but towards goals. My managers, colleagues, and pretty much anyone in the IT industry I know (Western Europe) all agree on that, and that it's not unheard of that almost the majority of us knowledge workers, do not work 40h/week, but less.