more ideas are welcomed.
Limit the number of "counterattacks"/defense episodes for one unit during a turn. Moreover, the number of episodes should be a special characteristic.
Now we see a situation where the strongest defender defends first and an unlimited number of times. In fact, a huge stack of garbage can be covered from attack by one strong unit. Which looks like a real fight in about no way. And yes, it's straightforward and boring.
Let's look at two examples to understand how this might work and why it's important.
1. My favorite artillery. Let's say enemy No. 1 has one heavy powerful weapon, and the opponent has a huge number of mortars. In reality, the super cannon will suppress several, and the rest will successfully damage enemy troops. That is why in our reality armies have a huge number of mortars, and not one "Big Bertha".
In the vanilla version, this will only lead to the fact that a large cannon will destroy an unlimited number of mortars.
2. Similarly, in real battles, real people were not omnipresent and tired. This was especially significant in the era of hand-to-hand fighting and heavy armor. And, by the way, this became one of the unobvious, but very strong advantages of light infantry after its appearance.
In general, as is obvious and confirmed by thousands of examples, a heavily armed infantryman, for example, was forced to leave the battle much earlier than his light colleague or cavalryman. And due to his lower mobility, he could not cover everyone. This is also why the armies were diverse and built on interaction.
And yes, for long-range troops who are not sitting right in the ammunition depot, the ammunition supply factor has always been significant.
The idea, in general, is for tough guys in ear-to-ear armor to be severely limited in the number of "defense episodes", and more lightly armed units to have greater "endurance", all other things being equal.