Much cheaper field training method

[mikwarleo]

I discovered this for the first time when running some game tests on field-training today.
Forgive me if this is well-known, I've personally not seen or heard of it before after 1000s of hours in game and much reading etc

In short:

When field-training units
it is MUCH cheaper to train pure infantry first and then switch the unit to your desired template

This works no matter what you're training (be it infantry, tanks, motorised etc).

In the spoiler below, I've added some screens and calculations showing some typical results from a larger number of tests I did today.

If the final unit you want to train is 'non-infantry', adding an extra step will improve efficiency further:

Non-infantry STEPS:
1. Train raw infantry (using a template with roughly same manpower as your final desired unit)
2. Switch the raw infantry to an infantry + desired support companies template. Try to have the same or less manpower than you had at step 1. To do this you might go from 22w or 24w raw infantry with no support to 20w infantry plus support. Train again to max.
3. Switch to final desired template (i.e. tank template or other non-infantry). This should have slightly less manpower than the template at step 2 to minimise XP loss and maximise efficiency. Wait for equipment to arrive, train again to max.

I ran a whole series of game tests today and found that this 'switching' method is at least ~45% cheaper (upto 70% cheaper) than 'normal' training of your desired template with no switching. It's also cheaper than adding a 1939 maintenance company for training. It's easy to reproduce the results in game if you want to test this for yourself.

Spoiler: Screenshots etc

Attrition did vary quite a bit when training the exact same thing regardless of these large variances, the ultimate result always was much cheaper for switching method.


TANK TEMPLATE EXAMPLE:

20w tank trained from green to regular without switching...

Attrition: ~321 production cost

@

20w tank with switching from a 20w infantry division following steps 1-3 described above...

Step 1. 20w infantry only
Step 2. 20w infantry + support
Step 3. 19w tank division

Attrition: ~137 production cost

OR: ~60% cheaper than previous test without switching

Also NOTE:
The PzII and SPA in the above tests both have heavily upgraded reliability, they're both 92% unit reliability PLUS 10% from maintenance company.
The difference between the two scenarios would be much greater, in favour of switching, if using regular ~80% reliability tanks/SPAs.

INFANTRY TEST

20w infantry with support but no maintenance company:

Attrition: ~332.5 production cost

20w infantry with support and 1939 maint. company:

Attrition: ~198.5 production cost

20w raw infantry no support, no maint. company:

Attrition: ~78.5 production cost (first stage, more to follow)

Changed to 20w infantry with support, no maintenance company, ready for final training:

Finished training above... final result:

Total attrition: ~104 production cost

OR: ~70% cheaper than training the same template unit from scratch (~332.5 production cost vs ~104)
OR: ~45% cheaper than training the same template + 1939 maintenance company (~198 production cost vs ~104).

NB: I did try training with just raw infantry plus 1939 maintenance company in the first step... raw infantry is cheaper. If you add maint. to raw infantry the cost of lost support equip far outweighs the savings on infantry equip.

The reason this works due to a combination of factors.
Firstly raw infantry is much quicker and cheaper to train than anything else. For example, raw infantry field-trains at ~3% per day when green, compared to ~2.3% for infantry + support or ~1.5% per day for tanks. Secondly, the infantry (or perhaps more rightly the manpower) retains a large portion of its trained-XP when switching between templates with the same (or lower) manpower requirement. Keeping manpower the same (or lower) cancels out the XP loss that occurs when units receive new manpower. By ensuring you only switch to a template with the same, or lower manpower requirement, you can limit the XP loss to 40% or less from template switching. If you're switching from 20w infantry + support to 20w tanks plus support ... that's a ~60% reduction on the attrition cost and training time of your tanks (of course infantry has some attrition cost to train but it's very small relative to a tank unit).

 

[BeauNiddle]

Yep it's something Secret_master likes to talk about. It's odd that the first 10xp you spend is REMOVING support battalions from a template but the 90 day training time for pure infantry is so much better than trying to train tanks directly.

Get a 24w or more pure infantry division with no supports, low priority, limited selection of weapons (so can never get latest). Churn them out, train them up to max and switch them over to what you want when you need it.

And if they over train and get you extra army xp then you know it only cost you out of date infantry kits.

Playing as UK I like to set a garrison order to guard only ports on constant training and have all my new recruits join that. Then I switch and grab units as needed. With the bonus that they can deploy around the world instantly since they start in a port.

 

[brainiac1530]

Contributing to this, infantry equipment has absurdly high reliability. It's 90% by default, and even the most advanced (1942?) infantry equipment still has 80% reliability. It's not unusual to train entire armies of pure infantry with daily losses of a few guns per day or so, which can be made up by a single mil. Add to this the low overall cost of equipping infantry, and this is the mathematically inevitable result, I suppose.

 

[FStefanak]

An important factor is that the attrition formula has a floor of 1 piece of equipment. Even when your reliability is really high and you only have a few pieces of equipment (12 artillery), you are still going to lose 1 piece of artillery when attrition processes (chance proportional to attrition %, 6 for training, 40 for mountains).
This is calculated separately for each individual variant of equipment you have in the division.
SO if you have 9 pieces of artillery I and 3 pieces of artillery II, you will lose 2 pieces (1 of each) .

That means you want to limit the types of equipment used to an absolute minimum and avoid mixing different variants in the same unit.
You may actually need hundreds of pieces of the same type for the reliability to kick in and make a difference over the hard floor of 1 equipment piece:

0% for 10 or under, 16.7% for 12 pieces, 58% for 24 pieces, 80% for 50 pieces, 95% for 200 pieces

Especially when playing Germany, all those foreign artillery pieces you get from occupied and annexed territories could severely increase your total attrition if you mix them in the field.

To limit attrition losses, it might be effective to restrict the training template to just one equipment variant (even if it means they end up under-strength)

Source:

Attrition and accidents - Hearts of Iron 4 Wiki

hoi4.paradoxwikis.com

 

[GrandVezir]

An important factor is that the attrition formula has a floor of 1 piece of equipment. Even when your reliability is really high and you only have a few pieces of equipment (12 artillery), you are still going to lose 1 piece of artillery when attrition processes (chance proportional to attrition %, 6 for training, 40 for mountains).
This is calculated separately for each individual variant of equipment you have in the division.
SO if you have 9 pieces of artillery I and 3 pieces of artillery II, you will lose 2 pieces (1 of each) .

That means you want to limit the types of equipment used to an absolute minimum and avoid mixing different variants in the same unit.
You may actually need hundreds of pieces of the same type for the reliability to kick in and make a difference over the hard floor of 1 equipment piece:


Especially when playing Germany, all those foreign artillery pieces you get from occupied and annexed territories could severely increase your total attrition if you mix them in the field.

To limit attrition losses, it might be effective to restrict the training template to just one equipment variant (even if it means they end up under-strength)

Source:

Attrition and accidents - Hearts of Iron 4 Wiki

hoi4.paradoxwikis.com

Restrict your training template to the basic infantry kit and put 1 MIL on that from the start of the game.

 

[mikwarleo]

An important factor is that the attrition formula has a floor of 1 piece of equipment. Even when your reliability is really high and you only have a few pieces of equipment (12 artillery), you are still going to lose 1 piece of artillery when attrition processes (chance proportional to attrition %, 6 for training, 40 for mountains).

This helps a lot thank you.

I might not have picked up the benefits of not mixing equipment (such as your arty example).

Also, I can now understand why it's cheaper to train pure infantry rather than inf + maint. co. (the 25 support takes much higher losses than it 'should' due to 1 piece minimum, and ultimately far outweighs the otherwise large reduction in infantry equipment losses).

I imagine it's still most efficient to go:

Inf no support > Inf plus support > Tanks plus support

Rather than:

Inf no support > tank div no support > Tank plus support

Or other possible variations? My reason being... while the latter reduces the time exposed to small equipment pools, it will also take much higher losses in expensive tanks/trucks/spgs. I also usually have 105 support equip in my 'expensive' units with all the support companies so that further reduces the small equip pool problem. I've not tested this specifically, it just seems it would be that way from the tests I did do etc. Please correct this if I'm wrong.