How are the recordings used while writing?

Whenever a book's Codex contains recordings that are switched on, the outline is planned from their summaries and key points, and each chapter is written from the passages that match its title and beats (the app searches the transcripts for every chapter, so even a ten-hour recording is used in full). The chapters cite those passages as (Recording title, mm:ss) so you and your editor can check every claim against the recording. This applies to every book, not only to books started with "Write a book from these".