Why are detailed and comprehensive Guru biographies considered more valuable for devotional practices like 'Parayan'?

The text from Chapter 0 explains that detailed, poetic, and comprehensive Guru biographies are highly valued because they are suitable for devotional practices like Parayan (a continuous reading) and Saptah (a week-long reading). The preface notes that while some famous poets have written biographies of saints, these are often too brief to be used for an immersive single-saint Parayan. A detailed work, such as the mentioned 'Guru Charitra,' allows devotees to fully engage with the Guru's life. This deep engagement serves a dual purpose: the writer performs Guru service, and other devotees who study the text can achieve the purpose of their lives, making it a profound act of public and spiritual service.