If you are breeding for show, you breed birds that look like what the Standard says. In order to do so, there comes a point when you have to get rid the birds that don't measure up. C U L L (how thats done ranges from the auction, to putting them in the freezer, or your choice.) In order to breed show birds you need to be able to hatch as many birds as possible and cull hard. We are guilty of keeping back extra birds here and there simply because they are female, or because they have particular personalities, but in the long run, they are just eating the feed that we could otherwise be feeding to a much nicer quality bird. (It costs just as much to feed a show bird as it does to feed a mutt.) I personally feel if you have birds "just to sell hatching eggs" you should be VERY concerned with the quality of those birds, that they meet their breed standards and they possess all the correct qualities for the breed, ie. laying ability, clean carcass when dressed out and other distinct qualities that make each breed the Said breed.
Our birds are culled throughout the year but mainly at a month, 6 months, 1 year, and after the first breeding season when replacements are growing in the grow out pens. We've even taken birds to a show in the past, seen them all together in show cages and culled them there. These birds are normally completely showable, but once they get into the show cages, sometimes they just don't stand right or we have others that just look better and we sell the "lesser" ones.