How does writing the biography of one's Sadguru compare to writing about worldly gurus or multiple saints in terms of spiritual benefits?

The preface in Chapter 0 presents a clear hierarchy of spiritual benefits. Writing about worldly gurus is seen as a worldly service with temporary importance that does not yield spiritual fruits. Writing about many saints is a step up, offering some spiritual benefits, but it is considered a partial service and insufficient for attaining the ultimate goal of salvation. In contrast, writing the biography of one's own Sadguru, especially when combined with dedicated study, Parayans, and Saptahs performed with pure devotion, is described as the best and most certain path to salvation and the most complete form of written Guru service.