I had to just write and say that you should take odannyboi's advice with a grain of salt. I know that a lot of people think that the early questions count more, but they don't. Read what it says in the Myth v. Fact stuff at the beginning of the official guide. I don't mean any insult, odannyboi! I really don't. But it sounds like his experiences are based off of a practice test, not the real thing.
For all verbal, you need to practice with official guide materials and use only those results to determine your progress. Don't let practice test scores be the sole determinant of how you're doing. If you can do the Official Guide questions without too much trouble, then you're ok. Don't worry about SCORES. Focus on questions.
I saw on your website that you're doing the power prep exams, which is great. I also see you're using M-GMAT tests, which are just punishing. They test SC issues that I've never seen in any real prep materials. I also read your post about how you're struggling with necessary versus sufficient. It sounds to me like you're working with M-GMAT material for your CR as well. Listen, my friend: don't worry about necessary versus sufficient! There are bigger fish to fry. That isn't likely to come up on the test. I've been doing this for a living for 8 years and I take the test 4 or 5 times a year. Trust me. It'll be ok. You don't need to learn that.
In the time you have, I believe you can do a lot to improve your score.
Focus on Official Guide questions. I think you already worked through OG12 (you talk about it on your blog). Hang on while I quote myself from another post: "If you haven't already, consider picking up Official Guide 10 (if you can find it on ebay or something, or borrow it from a library). There are lots of questions in there that aren't in OG 12. ( Also, the Verbal Review Guide -- the thin one. It doesn't matter whether you get ed 1 or ed 2, they're basically the same. Ed 1 is purple, Ed 2 is royal blue."
So what are you going to do? This:
Stop the marathon 6 hour study sessions. You're blowing a fuse, it's obvious to me.
You're going to learn to focus for 75 minutes at a time.
During a 75 minute study session, the phone is off, music is off. You don't move, you don't get a drink or a snack. You're going to do:
10 SC in 10 minutes
8 CR in 16 minutes
1 RC in 4 mins + 1.5 mins per question. (or do short passages instead of one long one)
Then you're going to review all carefully, reading every word of every explanation, whether you got the question right or wrong. Hang on, gotta quote myself again: "Their rationale is all that matters. It isn't enough to say, 'oh, I got it wrong, but now I understand....' Are you SURE you understand? Focus on what it was about the wrong answer that attracted you, because it may attract you again. Focus on what it was about the right answer that repelled you enough for you not to pick it, so you know not to let that issue distract you again."
That should take about 75 minutes. If it doesn't, then do more questions -- maybe 12 SC in 12 minutes, 10 CR in 20 minutes, and two passages. Make your set strong. Stay focused 100% for 75 minutes. Then go ahead and take a break.
Here are some quick tips on each one:
SC: look for patterns in the answer choices and focus on one error at a time. Go with what you KNOW, not what you think sounds better. Grammar and idiom must be correct. Style, not always. Not every difference between choices is relevant. There can be more than one answer that is grammatically correct, and in that case it's style.
CR: prephrase an answer before you look at the choices. it'll hurt at first, but keep doing it. Don't be lazy with yourself and say, "oh, that was almost what I put." One answer is right. Four answers are wrong. No two ways around it.
RC: focus on the structure and development of the passage, as well as authorial intention. Is s/he personally involved or just a neutral reporter? Does s/he feel aggressive or non-aggressive? For or against? What is the purpose of each paragraph and how does it contribute to the development of the passage? As a native speaker you have time to think about this.
I hope this helps!