Can you compare the different types of Guru service through writing and identify which is considered most effective for salvation?

Chapter 0 outlines a hierarchy of Guru service through writing. The first type, writing biographies of worldly Gurus like politicians or artists, is considered worldly service with temporary, limited fruit. A higher form is writing the biographies of many saints, which yields spiritual fruits but is still considered partial and insufficient for the ultimate goal. The best and most certain service for attaining salvation is writing the biography of one's own Sadguru. This act, combined with personal study, recitations, unwavering devotion, and faith, is considered the most effective path as it directly engages the body and speech in a selfless spiritual practice.