Experience has told me that it's actually the battles with more squads that are tougher to handle. The squads are smaller when there're more of them, but there are more total units and more total sources of damage on your units. Typically, getting hit 8 times means you take more damage than getting hit 3 times, even if the 3 hits are coming from a larger number of units. Of course, this also depends a lot on what units are present in those squads and even the terrain at times, but this is a more general observation.
Please aware the total enemy soldier are not change. If the total enemy soldier is 100, there are 5 squad. each squad is 100/5=20 enemy sodlier. if it is 4 squad, each squad will have 100/4= 25 enemy soldiers
Your experience is very different from me
A. My army size do not change. When enemy packed into smaller group. The army size is then bigger in a group. They hit will make 1 of my soldier group. And I will lost more and my army will be weaken
B. 1 group of soldier at edge can only surrounded by 3 enemy soldier group while it is at the edge.
It means even ...even enemy group has 1 million group, only 3 group of soldier can hit you if they are not range attack. You will not get hit by 8 times. It is 3 times only.
Nowaday, we are taking advantage of the stupid AI and using "landscape", "other blockage", "hit and run", "detour" ...etc to trap enemy and kill. Most of my battles is only just handle 2 to 3 groups only and section by section. The rest of 8 enemy group ( that is 5 to 6 enemy group) are keep away from battling.
The reduction of squad means the enemy ( 2 to 3 group that I normally faced ) is now bigger in size and more harmful and they can easily route thro blockage and come closer to hurt your soldiers
I have no idea ...how you fight..
Your words sound to me, you are doing 1 to 1, always move foreward
Please think , plan before move to fight...then you can enjoy the fun of battles ( how to fool the stupid AI)