Brainwashing and the feel good factor played it's role in the planning of Barbarossa a six month campaign and Hitler and Co drinking snaps in the Kremlin.
Someone forgot the size of Russia and the true logistic situation that faced them, in one respect Hitler was right to attack before the U.S.S.R caught up on the production front but Hitler forgot one thing. Stalin was a more ruthless son of a bitch and dug his heels in those dark days of 1941/42.