Let's test it, shall we?
If I want to pierce 1941 Panzer divisions, I need to be able to beat this template at the very least:
View attachment 207858
This division has these tanks in it:
View attachment 207898
What will it take to beat a division with 1941 Panzer IV's? It's October 1941. Germany currently has zero AT tech (thanks to focusing on other things).
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The tooltips tell me that I need 114 days to get AT Gun I.
If I want AT Gun II, I need another 152 days (the intervening tech plus AT Gun II itself).
If I want to get to 1941 AT Gun upgrades, I need yet another 76 days.
So, just to get to AT Gun I, I need 114 days before I build the first unit. Will AT Gun I suffice?
My template without AT looks like this:
View attachment 207853
Its piercing sucks, to say the least.
With AT Gun I
and a single AT support, it looks like this:
View attachment 207854
That ain't going to cut it.
What about one support plus 3 line AT?
View attachment 207856
That's not even close enough to pierce a panzer division with 1941 Panzer IV's.
What about AT Gun II?
View attachment 207862
With a single AT support, that's not going to work either.
What about 3 line AT?
View attachment 207865
Nope. You still aren't piercing the panzers.
Let's try AT Guns II with the 1941 upgrade.
With a single support AT:
View attachment 207867
With 3 line AT:
View attachment 207868
Nope. You
still can't pierce the panzers.
What about 5 line AT?
View attachment 207870
Woot! I can now pierce the panzers!
Okay, so if I swap to this template, how many AT Guns (and remember, AT Guns built under AT Gun I do not count) do I need to equip the entire German army?
View attachment 207872
I need 24,000 AT guns to fully outfit my divisions. How long will that take? (Note that I am still taking losses from enemy fire while I try to reach my quota, so simple math might not work here.)
I'll run the game and find out:
View attachment 207896
That's January of 1942. With 45 MIC on AT guns, I haven't even scratched the surface.
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That's March of 1942. I still haven't even come close with 45 MIC on AT Guns.
What's been happening since I started getting AT Guns out into the field?
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My enemy might have upgraded his or her tanks to armor 5. And what does this do to the divisions?
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Now those AT Guns are not sufficient to pierce. I need to spend another 74 days grabbing the AT Gun upgrade for 1942. That will give me this much piercing:
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Whew. Good thing I planned ahead and took care of AT Guns before the war broke out... Oh, wait, I didn't. I'm still trying to catch up.
Meanwhile, this is happening (if my opponent has any brains):
View attachment 207902
1943 medium tanks are in the offing. This means I need to spend another 100+ days on AT Gun III. The moment it's finished, I have to start producing them.
But I still don't even have enough old AT guns to kill existing Panzer IV's.
After a year, I am still over 7,000 AT Guns short:
View attachment 207903
By November, Panthers are starting to show up. If someone has saved army XP (or just has a ton), they are going to put Armor 5 on it right away.
View attachment 207905
They'll eat the reliability (besides, it's Panthers. They aren't supposed to be reliable in the first generation.) because this is what happens in the division template:
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All those AT Gun II's (which I still don't have built) are now obsolete. It's a race between AT Gun III and Panthers now. When AT Gun III is finished, this is where we stand:
View attachment 207907
But even after this adventure, I'm still not caught up on AT Gun II.
View attachment 207908
45 MIC on AT Gun IIs for 14 months did not solve my piercing problem.
If I had put 90 MIC on AT Gun production, it would still have taken more than seven months to get enough AT Guns in the field
on top of the 266 days (all techs prior plus AT Gun II itself) needed to research the tech that allows me to produce AT Gun II. (I can grab the 1942 upgrade while the guns build without causing a delay in production.)
If I put 180 MIC on AT Gun production, it would take me at least four months
plus the 266 day research time to get the AT Gun problem solved. But at this point, we're talking about making a huge shift in production that will impact everything else. Whatever things I was producing before with that MIC are now out of production
and if I want to swap back, I have to build up production efficiency again.
Then there's the whole tungsten issue. Each MIC on AT Gun II will cost 2 tungsten. Putting 180 MIC on AT Gun II will cost you the same amount of tungsten as 180 MIC on medium tanks: 360. That's more than ART costs. If you don't have that much tungsten, that's going to cost you 45 CIC to fuel. Trying to run ART and medium tanks and AT Guns will result in a deficit of tungsten that most nations cannot fully rectify in time to make a difference. Either you are already winning the war (in which case, you don't care about the AT guns), or you're screwed, because now you need to conquer Portugal or spend huge sums of CIC to fuel your sudden need of tungsten. And without that tungsten, your production will be slower AND the production efficiency increase will suck.
The bottom line is this: if you didn't bother to research any of the AT techs, and you find yourself being bulldozed by panzer divisions, you are going to spend 266 days plus a couple of months producing the AT Guns themselves
while cutting production to something else. And when it is all said and done,
you are doing it again right away because Panthers are on the way.
266 days plus four or more months is forever in a game like HOI4. The failure to plan ahead regarding AT costs precious time that could be better spent not swapping 180 MIC to an entirely new piece of equipment and trashing their efficiency.
Now, if you say, "But I don't need to do that versus the AI," then we're back to my statement that the difficulty of the game and AI is not the same thing as saying that there are few or no long-term consequences from decisions.