Keeping birds back until they are fully coloured, then picking the best birds for your own breeding program and selling off the rest- Are you kidding??

Now that I've taken my tongue out of my cheek, Tiaris makes a great point. We often dispose of our best young and forget about improving our flock in the long term. One of my avicultural laments is that fewer and fewer breeders these days seem to be keen to establish their own lines of species in which they continuously attempt to improve their strain. Where do we think the best birds come from? Breeders who have done just that.
Something worth thinking about, anyway.