Thank you for the Kudos!
For mental fatigue: I usually drink a vitamin B shot right before the test + sip on Gatorade and eat half a banana during my breaks. I also stretched in the bathroom. I practiced all this during my mock tests at home so perhaps you could do the same and find what works.
CR: This was and still is my weakness in verbal. I initially thought I'd just wing it and go with my instinct, and I ended up with V41 (94th percentile). But when I was determined to score at least a V45 (99th percentile), this is the strategy I used:
1) Read the passage and write shorthand notes / drawings to help you understand exactly what the passage is trying to say and who is saying it. (Learned this from
MGMAT)
2) Find the conclusion. I always underlined it and wrote a big "C" inside a circle next to it. Don't move on until you understand what it's saying. (Learned this from CR Bible)
3) Read the question stem. Recall the CR Bible to immediately recognize what type of question it is (there are fewer than 10 "types"). Recall CR Bible's exact strategies for eliminating incorrect answers. (For example, a question stem with "conclusion can be more properly drawn with which of the following information" is an Assumption question. Answers to Assumption questions typically contain the phrase "at least" or "none" and most like do not contain the phrases like "the main factor.") Continue eliminating until I'm left with one answer.
The reason I say Manhattan's CR book is a waste of time is that I didn't feel like it gave me enough question-specific strategies, just guidance on general process.
IR section: To me, this is just a combined quant + CR + Reading Comprehension section. I struggled with it too until I learned a few key strategies:
-Quant problems never give you more or less information than is necessary. Every "given" is used in some way to answer the question. IR questions, on the other hand, give you an overload of information so you have to figure out what is just "noise" on the page.
-Quant problems are designed to be solved by mental math or simplistic calculations. IR questions, on the other hand, should almost always be solved using the calculator + dropdown option to sort table information. There's a reason why they give it to you!
-When I took a practice IR, I did the first 8/12 questions, guessed on the final 4, and still got an 8. I used this information to calmly do the first 8 questions as accurately as possible instead of trying to finish all 12 in 30 minutes.
-The Multi-Source Reasoning questions are the most difficult and time-consuming. If you're comfortable with the other 9 questions, it might be in your best interest to skip these 3 altogether. The probability of success is lower since there are typically 3 sub-questions on the page and there's no partial credit given.
-Use AWA and IR as warm-up. I turned off a fraction of my brain during these sections, knowing the real deal would come afterwards. Skip any IR questions that might rattle your confidence, such as graphs you've never encountered.
I hope this helped!