Hey! So glad you found this thread! I still use neem but have done preventative treatments with less frequency because my birds have decided to hop down from their perches when I walk in the coop, no matter what time of night it is!!!
But they all have done surprisingly well despite that! I only treat my birds, i feel like it's too much work to do the whole coop but if I had a severe infestation I would probably treat surfaces in the coop too.
Don't forget you can use it as a dewormer internally as well! I am not sure how much you would have to use to affect fertility though, so if you want to hatch eggs, put off the deworming, just in case.
Sorry about the delayed reply... I think my BYC emails were going into my junk mail!
Thanks, @starlingdaly! I really appreciated the helpful info you posted.