I use a LOTTT of stone, so much so that mining it just isnt practical and is way too time consuming for the amount that I need.
So I made THIS!

At the top there is a machine that dupes TNT and explodes them into the inside of the machine thats set up to make as much cobble as possible through lava and water. It creates 320K cobble an hour, overkill but why not?
Then it goes into my supersmelter that turns itself on once items are in, it activates a carpet duper that feeds into the furnaces as fuel. It picks up the cobble stone and picks up specifically 48 pieces in about 1-2 seconds before distributing them across all 48 furnaces.
By the time the 1 cobble smelts another one is put into the furnace. AS SOON as it smelts. Its all very well timed to be efficient.
Too bad that there is no furnace that can smelt the cobble as fast as my cobble machine can make it.