Whenever somebody makes the deadly mistake to invade Russia, or during the great northern war, Russia seems impossible to capitulate. Even if there capitol has been moved 3? maybe 4 times. I think Russia should cap MUCH sooner, or at least offer surrender terms. the front line becomes larger than the front line during the German invasion of the USSR, becoming
impossible to maintain an army across it even if you sacrifice some spots.

Resistance also is a huge problem for smaller countries. Say you capitulate Saxony as Prussia, your military would not be able to handle the brewing resistance. Eventually after it hits 100%, the capitulated country will re-spear and your entire country will fall as you cant fight a war with already thin front lines and pull divisions away to another threat, often as strong or stronger than before the war you entered with it.
and if Poland appears, god save us all.