This is what we do. We raise between 20 and 25 meaties a year and do them in batches of between 4 and 6 at a time. We can do a batch that size in about 1 1/2 hours from start to finish, even with hand-plucking (which does get easier and quicker with practice). Aside from making butchering days more manageable, we like doing it that way for a couple of reasons. First, we can rest the birds in the fridge for a couple of days before further processing and freezing. Otherwise, I guess we would be managing the resting period in big coolers, which seems like a pain. Second, it gives us a variety of sizes. The first groups are around 6 pounds, which we like as whole roasters. The next group are around 7 lbs, and we cut those out into parts and freeze the breasts separate from the legs/thighs. The last groups we let get really big 8 t 11 lbs, and turn them into a year's supply of breakfast and Italian sausage.
I'm curious as to why she would think that the birds coming out of a factory farm and commercial slaughterhouse are more sanitary. The one thing I love about raising and processing my own is that I know that my birds were raised in fresh air, clean bedding and an open, and non-crowded environment, and that my butchering area is very clean.