Summary of Ottoman Empire's battles in Europe during the Growth Period (1453-1606) (only sourced from wikipedia):
Battle of Albulena: Albania - Ottoman
Albanians win, Ottoman 50-80k Albanian 8-16k
Siege of Jajce: Hungary and allies - Ottoman
Hungarians win, Ottoman 400-7000 Hungarian 4k-25k
Battle of Ohrid: Albania - Ottoman
Albanians win, Ottoman 14k Albanian 13k
Battle of Vaslui: Moldovia - Ottoman
Moldovians win, Ottoman 120k Moldovian 47k
Battle of Valea Albă: Moldovia - Ottoman
Ottomans win, strength unknown but casualties heavy
Battle of Breadfield: Hungary - Ottoman
Hungarians win, Ottoman 6-25k Hungarian 12-15k
Battle of Krbava Field: Croatia - Ottoman
Ottomans win, Ottoman 8-10k Croatian 10-11k
Battle of Mohács: Hungary and allies - Ottoman
Ottomans win, Ottoman 55k Hungarian 25-30k
Siege of Szigetvár: Habsburg - Ottoman
Ottomans win, Ottoman 100k Habsburg 2-3k
Battle of Sisak: Habsburg - Ottoman
Habsburg win, Ottoman 12-16k Habsburg 4-6k
Battle of Călugăreni: Wallachia - Ottoman
Wallachians win, Ottoman 100k Wallachia 10-15k
Battle of Giurgiu: Wallachia - Ottoman
Wallachians win, Ottoman unknown Wallachia 23-40k
Battle of Keresztes: HRE - Ottoman
Ottomans win, Ottoman 100k HRE 40-50k
So the Empire with a very low population density consistently fields huge armies compared to its opponents, gets blown up consistently but can't stop going further into Europe. Can someone explain to me what actually happens?