Why were some earlier biographies of saints, like those by Shri Dasganu Maharaj, considered less suitable for a dedicated Parayan or Saptah?

While Shri Dasganu Maharaj's poetic works like Shri Bhaktalilamrut are valuable, the text explains a specific limitation for certain devotional practices. Chapter 0 notes that if a devotee wishes to perform a Parayan or Saptah focusing on a single saint's life, these earlier works may not be ideal. This is because the biographies within them are often not comprehensive or detailed, sometimes spanning only two or three pages, which is insufficient for an immersive, extended devotional reading focused on one saint.