18-20 eggs seems to be the number they are usually aiming for. I have a broody bourbon red right now. She started sitting on a mixed breed clutch with turkey and chicken eggs. Then the neighbor two doors down found a nest of my other hen in her flower bed. I ended up taking the mixed clutch and put it in my incubator. Then grabbed the eggs down the road and put them under my broody BR hen. She now happily sits in a crate with 19 eggs, all the same hatch date. The incubator currently holds 19 turkey eggs( 12 bourbon red, 7 midget eggs white I bought at a swap) and 8 or so brown, green and cream colored chicken eggs.