Put it this way...
If you're a strong, competant Axis Germany player who is at war with Britain, the USSR and the USA at the same time, and fail to defeat the USSR before too long, you're going to have some long wars on your hands.
If you go to war with the USSR and no one else, have all of your flanks secure, and resources devoted to that one front, then chances are you'll end the war in a fairly reasonable amount of time.
If you're a strong, competant Axis Germany player who is at war with Britain, the USSR and the USA at the same time, and fail to defeat the USSR before too long, you're going to have some long wars on your hands.
If you go to war with the USSR and no one else, have all of your flanks secure, and resources devoted to that one front, then chances are you'll end the war in a fairly reasonable amount of time.