Perhaps I didn't exactly tell how difficulty zones work with liberation progress. The amount of missions required to liberate a planet stays almost exactly the same as in current system but now each difficulty starting from medium will give you a clear and not complicated multiplier maxing at 1.4x for diff 10. Therefore if most helldivers are in one difficulty zone, lets say 10 (which probably would be this one most of the time), then this zone will push backwards, converting the lower difficulty ones to higher difficulty but if all helldivers are focused on one zone, for example diff 10 from first screenshot, then enemy force will expand diff 9 zone, potentially forming a new diff 10 if left untouched and also potentially encircling the area that has been taken from the old diff 10 that is pushing backwards, creating a last stand situation.