I have five coturnix. They are around 8 weeks old. I still have half a 40 lb bag of food even though I've used more of it on molting chickens and as chick starter for my chickens then I've fed to the quail. So not much.
Young quail will eat a great deal more than adult quail. And feed consumption changes with time of year, breeding or nonbreeding season, winter or summer.
Coturnix do eat alot more than Bobs, just like Rock X Cornish Chickens, anything that matures in half the time i.e. 6-8 weeks for Coturnix is going to go thru alot of feed. Yes they are pigs but you can change their type of feeder to mostly eliminate most of the waste. They are Eatin-Poopin machines......