Just curious, that's all, because that's what I'm doing currently with the last book in my trilogy. I wanted to get started on writing it while Book 2 was in beta read, but was having some trouble starting. But I know exactly how the series will end, I know the character arcs and what should happen, and I had a pretty good idea of how the last many chapters should be sequenced. So I started writing the chapters in reverse order, and I've written 6 chapters so far with no issues, each connecting to the next and previous cleanly. I'm going to keep going back until I hit the point where I need to begin the normal write, which will lead to that junction.
(you could argue why not begin at the point from where I knew what would happen next, but I hadn't thought through that much either. But when I wrote the last chapter, it just logically started helping me write the previous and so on)
Just sharing... another data point that there's no one perfect way to write!