"The incredible daśā systems of Jyotiṣa are what give it such predictive power. The Bṛhat Pārāśara Horā Śāstra, that great compendium of astrological knowledge, gives 35 different ones, including nine conditional nakṣatra-based daśās that can be applied only when a birth chart meet certain criterion.
In this monumental work of over 400 pages, Master Jyotiṣī Marc Boney, presents each of these in great detail and profusely illustrates their efficacy in timing major life events using the birth charts of well-known individuals. He then presents his own case studies in which these conditional daśās were used to accurately predict.
Also included in this book is a chapter giving a systematic, step-by-step methodology for predicting with planetary periods in general, as well as one on how divisional charts are used to predict."