Some great photos! I wondered how large birds of prey (and others heavily dependent on flying/gliding) handle the molting process. We used to keep geese and ducks, and there just seemed to be feathers everywhere when it was molting "season." We could look at some of the birds and shake our heads and clearly see "You're not flying ANYwhere with those wings!" But those were domestic birds.
Appreciate the detailed explanation!
Birds like game birds, some water birds like ducks, loons, etc are able to go to safe places with lots of easy food and lose all of their feathers at once, eat like crazy and regrow them all at the same time. They are flightless at that time but can usually survive, so the strategy works for them. Most other birds molt sequentially, i.e. all their flight feathers in a sequential order until the molt is done. Very large birds with huge flight feathers use the strategy discussed above. I find molt interesting. Are you a birder? If so check out @birdersofsteem.