It could be a cultural thing. In Spain and Ireland (where I've work), if there is some extra time involved, it's not compensated, unless it is very serious and requested from management (working weekends, etc) My impression is that some people just get a higher workload and work overtime "to catch up" without telling anyone. Of course that's a bad idea, as your manager won't probably notice that you are working overtime, and will increase again the work load "as you are capable of handling it".