Why are some saints' biographies considered unsuitable for a dedicated Parayan or Saptah, even if written by great poets like Shri Dasganu Maharaj?

While the writings of poets like Shri Dasganu Maharaj, such as Shri Bhaktalilamrut, are valuable, Chapter 0 points out a specific limitation for performing a Parayan or Saptah of a single saint's life. The issue is that the biographies of individual saints within these larger works are often not comprehensive or detailed enough. The text specifies that these accounts might only take up two or three pages, which is insufficient for the deep, focused study that a Parayan requires. Therefore, for such devotional practices, a more detailed, standalone biography is considered more suitable.