I check them after I pull all the chicks, If candle shows no internals I toss. I dont even look for life. I had one I left in this time because I had a serama in late that was found under a hen that was unknown date but tossed it then anyways.
it takes a few hatches to pick up on this, also fine tuning your incubator and you skills at it
SWEET! birdies!! great photos too!!