I am a university professor from the United States. I am on a one year "leave of absence" from my US university, and I am now in France working for an industrial research organization (high level R&D at a prime nuclear research center in the world) to improve my technical skills. I have had little experience outside of university settings until now.
I have a bit of a quandary at my current workplace. I have a boss who likes to work between 9am and 8pm and is always extremely tense and strung up. He expects a similar level of commitment from me that was not negotiated as part of a contract. Now, I understand that in research, you can't always negotiate a contract's clauses down to the last inch, as then it wouldn't be called "research", but you do generally have "hours spent at work" outlined.
I am on salary. My contract states that I will be paid for 35 hours of work a week, but my manager has made it clear that "I do not work as long as other folks in the research lab". (Most of them spend 10-12 hours a day at work). His manager feels that, although it's not entirely fair to make such unqualified comments about my work, I should work for 39 hours a week and that the working hours are 8.30am-5.10pm. (They are not really published anywhere).
I know that I have a certain attention span that allows me to work from 8.15am-5pm. After this I am quite spent, and I know that not much inspiration is going to pour out of me. At 5pm I prefer to leave since I have items in my personal life that I need to manage as well.
I hate quibbling about "how much time must I spend a day at work", but now I just stick around until 5.10pm (8.15am-5.10pm). On some days, I know that I have done enough on my daily task list at say 4.00pm, but I just sit around for the next one hour twiddling my thumbs doing nothing constructive.
I personally hate sitting around trying to appease a clock, but is this what is expected at a "real/corporate" workplace? All my life I have spent in university settings where people don't "time" me.
Is there anything wrong with leaving work early when you know that not much productive is going to happen in the last three-quarters of the hour or so?
Things I cannot consider:
Quitting my job.
Hiring a lawyer (I doubt this is a case for such a step).
Work 10-12 hours a day. This, I think is absurd. Spending "a lot of time at work" doesn't necessarily translate to "getting a lot of work done" when you must manage work-life balance/priorities.