X 2 --Agreed!!LOL! Bee, I am going to give you some advice that I got from your old-timers thread (and others) way back when. It goes for all of us. Especially me.
Don't get all wrapped around the axle about this stuff. Breed chickens. The birds will tell you if you are improving things or not. If you have a specific breed, breed toward the standard. If you are raising your own backyard mixed-breed flock, breed toward whatever standard is in your head. Most of us want healthy productive chickens. So breed from the healthiest, most productive, best-looking chickens you've got. If the next generation is better, great. If the next generation is worse, change what you are doing. In Bob's words, KISS. Keep it simple!
If you get birds from somewhere else, know that they may react differently at your place. Be prepared to hatch and cull a lot until they have stabilized and are back on track, having adapted to the new location.
Kicking the can down the road...
Sarah
P.S. Most of what I know about raising chickens has come from Beekissed and Bob Blosl and Walt and from many of the other folks on this thread. For which I am hugely grateful. Without you all I wouldn't have had a clue. Thank you.