ORIGINAL: Gunnulf
T66 Caucasus
... Currently despite holding Maikop and in theory trains from this railyard helping push supplies out to 30 hexes which should be getting more supplies to this eastern tip, in reality this rail branch is carrying barely a trickle despite 11 Armee being the only one at priority 4 right now. We get enough to keep the units doing ok, especially with these being priority for air resupply, but certainly not accumulating fuel and supplies up close to max like I would hope. If we can get Ordzhonikidze and turn it into a superdepot I am hoping this will work better to pull supplies than Maikop is doing to push string.
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Just a small quibble that may have some bearing on your (impressive) operational goals.
If a depot is going to send freight by rail to another depot it pulls in the 'trains' (for lack of a better word) from level 2 railyards up to a 30 hex (by rail) radius. There are only a few in this region probably just Maikop and Krasnodar. Once entrained, that freight has 200 SMP (and all the stuff about SMP/hex, congestion etc). Key is trains are only used for depot-depot transfer.
depot-unit is trucks (or horses), and again there is a 30 hex max range for this draw. Also unit priority doesn't really affect what supply is sent to a given depot, the depot priority does. Clearly there is an interaction but its not cause-effect, more consequence-effect
I agree this is a good choice for a super-depot, I'd actually do that at Maikop now, you need that extra pull from the wider logistics system.
You may be doing this, but I'd put Rostov and Stalino to pri 4 depots too. That will grab and build up supplies, once there is a decent stock there, drop them to pri 1/2 and - esp linked to a super depot - that should poke a decent one off bonus allocation down into this region