not necessarily ...
on the IC trains it does if you schedule which train you are catching but not on the general pkp trains.....
but in my experience 1st class is generally empty on pkp trains except at rush hour times between cities like poznan - wroclaw as theye dont have IC trains
IC trains are the ones which are fast and only stop at major cities(also much more expensive (ie:poznan -krakow pkp 78zl IC starts at 135zl depending on time)
this site tells you more than most train stations can..
http://rozklad.pkp.pl/bin/query.exe/en