Poland is one of the hardest-working countries in Europe, at least if we consider the average number of working hours per week:
Average working hours by European country.
However, if we consider effectiveness at work, the picture becomes more complicated. One standard measure - GDP per person per hour - places Poland 28th in the world. Which is 23rd in Europe, as only 5 countries in the top 30 of that table are outside Europe: the USA, Australia, Japan, South Korea and Israel.
This measure can be disputed, however, since GDP may depend on other factors than employee efficiency.
Sources: Eurostat, Expert Market, World Bank data
pt
