Wait! I usually answer these as I read, in order, but I'm coming up to the top to say something important: DON'T TAKE A CAT EVERY DAY (or every other day). That's like training for a marathon by running a marathon every day - you just tire yourself out!
Take a CAT once a week. On other days, set up a 2 hour study session by planning EVERYthing you'll do in advance. Then study for 2 hours straight with one 10-minute break in the middle. I know this is shorter than a test, but studying is actually more tiring than taking a test. (When you're studying, you're trying to make new memories and learn things. When you're taking a test, you're just trying to remember stuff - that's easier.)
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Yes, idioms are very difficult for non-native speakers. I am terrible with idioms in French.
Yes there were also a time problem with RC; I spent too much on this section and then I rushed in the last question.
Do you mean you rushed the last RC question? Or do you mean you had to rush on the questions at the end of the section because of the extra time you spent on RC? If the latter, then that's why your score dropped at the end - you were rushing. (Fatigue may also have been a factor, but rushing is an even bigger factor!)
Read the whole passage and, after each paragraph, summarize the content in my mind but without taking notes that steal too much time.
I'm going to amend this a bit. Read the first sentence or two of a paragraph; that tells you what that paragraph is about. Jot down a VERY short note (5-6 words max) about that paragraph. Read the rest of the paragraph much more quickly, without taking any notes, UNLESS you see a big "change of direction" word like however, but, yet, etc. If there's a big change of direction that gives another big idea, note that idea down too.
Then go to the next paragraph and so on. So DO take notes on "big ideas" but do NOT take notes on details. Don't even read the details very carefully - you might not get questions about them! (And, if you do, you can come back and read carefully later.)
[Okay, this is where I got to your comments about the CATs and I answered that up at the top.]
For SC, do you have our SC Strategy Guide? I don't normally actively tell people to buy one of our products, but honestly, our SC Guide is the best. :) Don't just take my word for it - ask your fellow students. In particular, you mention struggling when the questions get really tricky, and that's where the grammar lessons in our SC guide will really help you.
Re: your average scores vs. your overall score - yes, that means your score is dropping towards the end of the section. Your final score is basically whatever level you're at when the test ends (because the test is recalculating your score after every question). So we do want to fix that drop, and yes, stamina is likely a factor. I do think you need to take a look at the timing as well, from what you described - even having to work 15 or 20 seconds faster than usual can cause you to make mistakes on things you can normally get right, especially when you're already tired.
Also, for both CR and SC (and RC), start doing what I described in my last post with respect to analyzing the answer choices (why a wrong one is tempting, etc.).