Can they do all of that simultaneously? What happens if they get crowded all along the line? There is no need to push to Moscow. Moscow would get perturbed if they lost the Kola, Kaliningrad and St Petersburg. Concurrent loss of access to Crimea through Euro-Turkic domination of the Black Sea. The job for the Poles, with the Brits and the French, then becomes to hold in the centre - which is what a Schiltron (oops sorry, porcupine) is optimized for.