How does a book end up reviewed in the New York Times

How does a book end up reviewed in both the New York Times Book Review and the newspaper’s Arts section, while the the book’s author is writing essays for the paper (and sometimes even being profiled for it)? New York Times Public Editor Margaret Sullivan explains how Times fiefdoms divide their assignments: “The Times’s three staff book critics—Michiko Kakutani, Janet Maslin and Dwight Garner—make their own decisions about what to review. They do so without regard to, or knowledge of, what the editors of the Sunday Book Review, a separate entity, may have assigned or have planned.” nyt.