How big is an ingot? A cubic meter of ore (about 4000kg of ore) could easily have many ingots worth of metal there, but need advanced processing. Also, the extractor is in fact based off of a real ore processing system, a "steel ball mill".
Well, if you want to talk realisim on this front I have several problems with the extractor (over and above its multiple processes in a single step nature).
It is true that hematite ore can have an mineral load of up to 60% iron. And, given that 9 MC ingots can be combined to make a cube of metal, its not unreasonable to expect ~6 ingots of iron per processed iron ore (assuming its hematite). Other iron ores can have iron contents as low as 15% but lets assume hematite.
Now, its a mod mineral not vanilla, but Aluminium is typically extracted from bauxite ore - via a two step process - first to alimina, and then to aluminium via high temperature electrolysis.
Likewise, Silver is usually extracted as a 'trace' constituent of galena ore - which is usually far more predominantly lead.
Copper, Tin, and other common (modded) minecraft minerals all have different (real world) ore compositions, processing, and yields.
I do not bring this up as a criticism of a mod that I am enjoying loads. Its just - in a mod so focused on realism - it seems possible to step away from a 1 size fits all approach to ore processing, and actually build different ore processing setups for the various ores. Based on actual yields & processes. Its not that I need more excuses to expand my RoC workshop...
I do love the extractor. But it makes me feel just a little bit dirty when I smelt my diamond flakes to recover pristine diamonds.