Why is there such an emphasis on having a detailed biography of a saint? What's the benefit for devotees compared to shorter accounts?

The preface emphasizes detailed biographies because they are suitable for devotional readings like a Parayan or Saptah focused on a single saint. As Chapter 0 clarifies, shorter accounts, such as those found in the works of poet Shri Dasganu Maharaj, are often not comprehensive enough for this purpose, sometimes spanning only two or three pages. The benefit of a detailed work is twofold: the writer performs a great service to their Guru, and the devotees who study it also achieve the purpose of their lives. This act of collective reading and study allows the writer to gain the merit of serving God in humanity (Jan-Janardan), making detailed biographies a powerful tool for spiritual service and growth.