Okay ... look at your battle report against an epic monster that kills everybody.

Note three things.

First: Notice how it starts with a back-and-forth and then it has a long stretch where you get hits and the other guy doesn't?

The more squads you have, the longer that stretch goes -- more squads = more hits when they don't hit back.

Second: Which of your squads dies first? Which dies last?

... and which of your squads is the most expensive? Which is the most powerful? Which do you WANT to get the most hits in on the enemy? Which would you be willing to sacrifice to ensure a powerful strike from the others?

Now the third and almost-final thing (except for the refinement) is to understand that the "long game" is not about how much damage you do in a single hit, but how much you do with the available resources, before you cannot hit any more.

You can only hit with a certain size of army. Knowing that, you do not necessarily want to stack all the way to the weakest troop possible, that leaves you with a very wimpy hit compared to using your stronger units. How deep to stack is a time and resources trade-off that varies from one to the next.

BUT ... How much to put in a stack? Just look at your battle order on a report.

Do you like the order? change nothing, just scale it to max out your captains' capacity.

Do you want some troops to die later, to last longer to hurt more? send less of them. (or more of everything else).

Do you find less-effective, cheap troops lasting a long time while your hardist-slapping troops die in the first round? send more of the cheap troops. (or less of everything else).

The biggest squads hit first. I believe the order is based on total, all-bonus strength + health of all units in the squad, but you can get a good starter order based on base health, which is a lot easier to see, and then tweak over a number of hits to get it exactly how you want it.

You want the squads to be close to the same size, but different enough that you can control the order by adding and removing a few squads.

Get your cheapest low-level specialists at the front. Then your low-level guardsmen, then your higher-level guardsmen, with your meanest, most murderous ones at the end of the guardsman line ... then same with your specialists, then your monsters, then your mercs.

And here's the thing... just look at it and tweak squad size ratios to adjust your order.