Can I use the works of Shri Mahipati for a detailed week-long study (Saptah) of a single specific saint's life?

According to the source material, this would not be ideal. While you can perform a Parayan or Saptah of Shri Mahipati's complete works, such as Shri Bhaktalilamrut, they are not suitable for the detailed study of a single saint. Chapter 0 explicitly states that the biographies within these larger collections are not comprehensive or detailed enough for this purpose. It is pointed out that the section for any given saint might only be two or three pages long, making them insufficient for a focused, in-depth Parayan.