Don't know anything about drilling rates myself. I have only broadcasted milo in a mix but usually just look up recommended rates on the bag and go from there. Too many seeds competing with each other gives you smaller plants and thinner coverage will give you bigger plants. Also depends on your goal---soil improvement? Feeding wildlife? Screen? If looking to build up organic matter I've heard that mowing the milo after it's half grown will make the plants create a lot more root system which gives you more organic matter to build.