Yes but Jan Dlugosz (a 15th century chronicler) wrote that Lithuanian banners were smaller than Polish. Besides - we know the size of some banners (both from Polish & Teutonic army and other armies of that time) and basing on this info we can assume what was the average size of an average banner.
For example the Teutonic banner of mercenary knights from Meissen at Grunwald numbered ca. 750 men (including 80 knights-lancers + 299 squires-lancers and around as many mounted crossbowmen as lancers in total). Of course this banner was rather among those bigger than average.
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That's partially why Bohemian crown lands have been more developed than any other central European 'country' (Poland and Hungary).
You ommited the part: "The same took place in Poland". And in Hungary.
So I don't think that this is the reason why Bohemia was more developed. The reason was rather that a) Bohemia had more natural resources (especially deposits of various minerals and metals) and b) Bohemia had bigger population density - and this had been the case yet in period when Poland was an infant as a state (in 11th century Poland had ca. 5 people / km2 while Bohemia 8 people / km2; then in 14th century when Poland had ca. 10 people / km2, Bohemia had ca. 15 or 16 people / km2). Hungary on the other hand also had many resources (just to mention Hungarian gold mines), but had low population density - the Mongol invasions contributed to this situation too.
In Poland the Mongol & pagan invasions only devastated eastern and southern parts of the country (including some towns plundered west of the upper & central Vistula). But significant population decrease was observed only east of the upper & central Vistula, in the Lublin province (where population density was in the range of 1 - 3 people / km2 while west of the Vistula and San it was much higher, with the highest density of 20 - 30 people / km2 in the region of Krakow and over 30 people / km2 in the area around the town of Wislica).
Anyway the advancement of Bohemia was not much bigger than other countries of the region, Poland & Hungary. And maybe I'm wrong but it seems that Silesia region was more developed than Bohemia, even yet before Silesian dukes started to pay tribute to Bohemian kings.
Silesia had rich natural resources (including gold mines) so when Poland lost Silesia in 14th century it was a really painful loss. Casimir the Great attempted to regain Silesia but in the end he abandoned his attempts (in exchange for a certain sum of money and declaration of Bohemian king that he would not claim rights to the Polish crown) and focused on expansion into Halych-Volhynia instead. The Jagiellon dynasty wasn't interested in westward expansion. I wrote an essay about dynastic policy of early Jagiellons long time ago. They had many good opportunities of regaining Poland's lost western territories (Silesia, Western Pomerania) but unfortunately did not exploit them. They were more interested in eastern policy.
By contrast, Poles learn about their greatness, how they civilized the wild poverty-stricken barbarous east and saved Europe from the vilanous Turk, and then the long era of being oppressed and then kept away from their true inner westerness by the evil chop-stick using Russian.
There is not that much focus on Poland in pre-university history education in Poland. On the other hand there is also not that much focus on the
Age of Imperialism + the "classical" ages - as you wrote regarding the western history education. In Polish pre-university history education it seems that similar attention is devoted to each historical era. There is a separate handbook for each era (usually something like: Prehistory & Antiquity; Middle Ages; Modern Era; 19th century; 20th century). Of course the same can't be said about each country / civilization. Usually everything is Eurocentric. But this also depends on level of education of a particular class - whether it is a class with basic or extended level of history education.