The disparity in Vimshottari Dasha analysis between astrology programs, such as Jagannatha Hora and others, primarily arises from differences in the Ayanamsa applied (the adjustment for the equinox's precession). Various software might adopt different Ayanamsas (like Lahiri, Krishnamurti, Raman), leading to minor discrepancies in planetary positions and Dasha timings. The precision of Dasha analysis is contingent on the Ayanamsa you adhere to, making it crucial to remain consistent with your chosen system. Jagannatha Hora, utilizing the Lahiri Ayanamsa, is often considered dependable. However, the crucial aspect is aligning the Ayanamsa and data entry for precision.