What are Parayans, and why are some devotional texts considered unsuitable for this practice?

A Parayan or Saptah is a form of devotional reading of a sacred work. The preface in Chapter 0 explains that for a text to be suitable for this practice, it must be comprehensive and detailed. Some texts are considered unsuitable because they lack this necessary depth. For instance, the works of Shri Dasganu Maharaj are mentioned as containing biographies of saints, but these are often not useful for a Parayan of a single saint's life because they are too brief, sometimes spanning only two or three pages, which is not considered comprehensive enough for this purpose.