Wanted to thank the people who provided info on this. My Amazon has had annual molts which varied a lot in length of time. The reason I was searching for info on the topic is that she has been moulting for at least three, maybe now close to four months and she's not done. She looked really scruffy for most of that time but recently (within the last few weeks) is back to looking like her gorgeous usual self ... even though she continues to moult.
I've kept major feathers which dropped at home (no idea how many I've missed on walks or hidden in floor paper or cage litter) and she has cycled through most of the tail and the four red-banded wing feathers (each side).
Someone commented on how messy it is. In our case it's like living in the aftermath of a pillow fight, which fortunately doesn't bother me. I also have a lot of houseplants, so things are dropping off all the time everywhere.
She still has some significant gaps in the primary flight feathers, which I find a little odd, but given how long this has been going on I'm not going to get worried yet. She has had several instances of dysmorphic regrowth of two flight feathers (no recurrence in this moult afaik) and I'm waiting until it appears she's pretty much at the end of her moult before taking her in for her annual (now rather late) checkup.
Any case, thanks for the info and happy holidays.
Oh, P.S.: From her doctor I understand that they lose the large feathers bilaterally, synchronized, essential to keeping them balanced and operational in the wild. From what I've observed, that's indeed the case.