I have cleared my LSA Readiness Exam last month and this exam really designed to test our knowledge on the subject which are mentioned in the readiness guide. Please make sure you go through all the advance topics and thorough on those along with reference of application design from CSSA course.
There is a Readiness Exam prep course available which you can sign up for on Pega Academy here. The course is a 3 hour virtual presentation which is free and consists of an overview of all test domains and sample questions from each domain. (see attached for schedule). If a session is indicated as full, you can still attend by sending an email to Education@pega.com specifying the course name, date, and time zone and they will manually enroll you in the course.