I would say there is "doing your job" and "overdoing" if you work 8 hours productively that should be the deal with your employer. Sure, if there is some crisis

I would say there is "doing your job" and "overdoing" if you work 8 hours productively that should be the deal with your employer. Sure, if there is some crisis maybe stay a bit longer to help the team. But going out of your way to save the company money in transportation is a different kind of issue, and so is regularly overworking.