I don't see it as a defensive tool at all.
I'm not saying it the best use for it, but I'm seeking to get the most use out of them, and wondering how they work exactly in the mechanics of the game engine.
You could put them on reserve I suppose, but, I think other units are better suited for this sort of thing, and arty SUs are more likely to react and don't take up map space.
Bear in mind that there is a limit to the amount of units that can react to any given battle. I'd rather have a rifle division show up than an artillery division.
So they must be in reserve mode to participate in defense of an adjacent hex? That's what I'm trying to clarify.
To that end, how does the Reserve commitment flow exactly? Does a commitment check occur each battle for each unit available (sufficient MP and reserve status), or do the command checks take place, and if successful then an available unit is chosen (randomly?)
On map artillery is what you use to blow up enemy entrenchments. You don't build it for defense.
I'm not trying to suggest that, I'm just wondering how/if they can be utilized during the opponents movement phase.
The penalties are with respect to CV. Artillery has negligible CV. Its role in battle is not to occupy ground, which is what CV ultimately determines. What artillery does is blow sh*t up or disrupt the enemy and make it possible for those elements that actually do contribute to CV to occupy or take ground. It's there to suppress enemy CV, in other words, not to contribute to your own.
So the -30% penalty doesn't mean only 70% of tubes are firing, it just affects the odds calculation for who takes the hex after all the firing is done?
I want artillery, when available, to suppress the enemy CV (e.g. Voronezh Front bombarding 4th Pzr Army as they staged to assault at Kursk).
If the -30% penalty is reducing tubes in combat by that amount, then assigning on map artillery to Stavka means you have to build roughly 50% more to have the same punch as if it where assigned at the same Army level. That trade off may have plenty of merit, but I'm trying to get a handle on the benefits/penalties to decide.