Lately, I've encountered major resistance to the following points in my original list:
8) At the first sign of respiratory illness, i.e., discharges from nose or eyes or bad smell, cull, cull, cull...birds don't get colds, per se; they contract diseases, many of which make them carriers for their lifetime. That means they are able to infect others even if they seem to recover themselves. See Rule #7.
9) Do not medicate unnecessarily, including wormers and antibiotics
The logic seems to be that it's so easy to get CRD/ Mycoplasmas, Coryza, etc, etc, that you should just treat with antibiotics and keep your birds; why bother culling when you can just get it all over again? I do not believe that it's as easy as all that to keep getting illness in the flock if you practice good biosecurity and all that entails. If you get illness in the flock and you depopulate yet, you keep managing the way you were when they became ill in the first place, yeah, sure, the new birds will become ill eventually, too. And if you aren't careful where you get them, they may come to you already infected with something.
Hatcheries would have you believe that ALL flocks in this country have CRD. That is absolutely not true. My birds who have gone to other people's flocks have been tested through NPIP and have been found clean of those diseases. That isn't to say my flock will never have it-anything is possible, sure. It'd be easier to avoid germs if we could see them, right? Well, germs may sneak in here, in spite of all my best efforts, however, just because CRD is considered common, does that mean I should just shrug my shoulders and give up trying to keep it out? No.
Speaking for myself, I will never give antibiotics to any bird with any respiratory disease. Even if I did not sell hatching eggs and chicks, I do not want a weak flock who becomes ill at the drop of a hat. Even if I wanted to keep them in spite of having had that disease and even if I further closed my flock, I still do not want birds that cannot fight off CRD/Mycoplasma on their own. That is my philosophy, which is what this thread is all about, what I do. No one has to do what I do, but I can tell you that, so far, it's served me very well.
All that said, in the Emergencies & Diseases forum, we daily have people desperate to save some bird who has contracted Coryza, or ILT, or CRD, etc. They will grab onto any life preserver that is thrown, no matter if it floats or not. You will see that I rarely go there any longer because I will not give someone advice that I feel is irresponsible or wrong or that is contrary to what I feel is the very best thing to do for their flock. What each person does is entirely up to him/her, but you won't get sugarcoating from speckledhen.