3,000 rounds per day, is 150 tons, or about one ton of shells, per gun, per day (plus propellant), or one big truckload per day, for a battery of six guns. A couple of dozen rounds fired per day, per gun. Seems quite a sustainable rate of fire.
I don’t believe estimates of the Russians firing 50K shells per day, on a sustained basis. Maybe they massed fires like that for some peak at some point.
However many tubes/crews they had working, they have been subject to attrition and suppression from counter-battery fire, and now their resupply of ammo is under attack.
I suspect that when you add in the greater accuracy of the Western guns/rounds, Russia’s Artillery dominance of the last phase of the war, is not going to carry forward to the next phase.
Instead, Russian forces will have to adapt to the new Ukrainian deep strike capability, throughout most (if not all) of the occupied territory, outside of Crimea.
[I don’t believe estimates of the Russians firing 50K shells per day, on a sustained basis. Maybe they massed fires like that for some peak at some point.]
https://encyclopedia.1914-1918-online.net/article/artillery
That averages out to 150K shells a day. 1/3 of that doesn’t seem like much of a stretch for a 21st century economy with a much bigger surplus (beyond subsistence) than Germany’s a century ago.