Well from what I researched there is no real consensus… some feel its useful as a review but only after studying all the materials atleast once, while others feel it is too condensed…
I am considering taking it from a perspective of speeding up my review and getting an overview based look at the concepts along with specific questions for each concept from the exam workbooks.
Usefulness vs mock exams, schweser notes and EOCs is definitely debatable but each serves a different purpose in my opinion… schweser notes –> understand concepts, mock exams –> practice practice practice which apparently is the key to clearing L-2, EOC –> checking concept understanding as per CFAI and 3 day review - simply to review/refresh and put together concepts in a time effective manner and does not substitute practice…
So to conclude is 3 day review needed to pass - possibly not but can it be one of the things that help you pass - possibly yes… Long post but hope that helps…