You shouldn't do this. The Polish Ministry of Foreign Affairs says:
A D-type national visa permits to enter the territory of the Republic
of Poland and to stay continuously or for several successive times in
this territory for a total duration of more than 90 days during the
period of validity of the visa, but not longer than one year.
A D-type ...
Deutsche Bahn has a toolbox called Ist mein Zug pünktlich?.
They also publish statistics.
Both are an authoritative source.
To my experience, delays are worst with regional trains as they wait for delayed IC/EC and ICE trains so passengers won't miss their regional connections.