Germany was aware that they were facing an opponent in Russia that could lose the entire population of Germany and still have enough national manpower to fill its armies. Germany was aware that their machines of war were complex and slow to manufacture.

Yet aside from a brief time in 1941 when they actually used their famous 'blitzkrieg', they used the prepared frontal attack that was the preferred method of attack in 1915 on the Western Front. As a result, they took losses in manpower which they simply couldn't replace and losses in equipment that would take a long time to replace.

It's not like the Eastern Front in WWII was a continuous trenchline like the Western Front of WWI. There were always ways to go around fortified positions. Yet the Nazis--or rather, Hitler and the cronies he promoted, insisted on attacking right at the Russians.

Even in 1945 in Poland, they try to slow down the Russians by attacking their columns where they were strongest.