The problem being, the speed limits are ridicules. It should be at least doubled. Then I'd be willing at least to consider it. As it is now, when seeing 50kmh limit on two lane road, I just mutter "They got to be kidding" and ignore it.
In Britain, you'll find a 30mph limit (slightly lower than 50 km ph) on many two-lane roads ("dual carriageways") in built up areas, Where the lamp posts are close together, you are also supposed to know it means 30mph. Such roads are often covered by speed cameras and more recently average speed cameras which measure your vehicle speed between extended distances so you cannot just slow down for the speed camera (foto radar). In Essex, there is now a stretch of about 15 miles with a top speed of 50mph on a dual carriageway (the A127). It could be more than 15 miles, I'm not sure. It has average speed cameras all along it, reading registration plates. That then becomes 30mph as it nears the built up areas and you have cameras all along.
If anything, because of the poor state of Polish roads in some cities and towns, the speed limits should be reduced. 40 km ph around Wroclaw's side streets would be fast enough all things considered. On the main arteries that are straight and pedestrians and hazards are easier to perceive, perhaps keep the 50 km ph.