I suggest that you adopt a prep strategy consisting of
topical learning and practice. In other words, focus on just ONE topic at a time and practice that topic until you achieve mastery.
For instance, consider your study of Assumption questions in CR. First, immerse yourself in all aspects (e.g., definitions, techniques, strategies, etc) of this topic, and then, focus solely on answering Assumption questions. After each problem set, take the time to delve into your incorrect answers and what caused them. Did you fail to consider a key aspect of the argument? Did you fall for a trap answer? Did you misinterpret the given information or aspects of an answer choice? This kind of self-reflection is a powerful tool that allows you to understand your learning process and make significant improvements.
By meticulously analyzing your mistakes, you will efficiently address your weaknesses and, consequently, enhance your GMAT CR skills. This process has been unequivocally proven to be effective. Assumption questions is just one example; be sure to follow this process for all CR question types.
Also, check out these articles:
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GMAT Critical Reasoning: 8 Essential Tips-
The Phases of Preparing for the GMAT