Thank you experts for your warm responses and suggestions!
I ordered the ESR report today, and contrary to my expectation, CR is actually my strongest verbal sector (with 84th ranking, the same ranking I gained in my test in December). But my RC and SC rankings declined. Both fundamental skills of RC retreated, a result that might partially be attributed to the fact that I kind of rushed in the final passage. The fundamental skill "communication" in SC improved, but another skill "grammar" fell, a very surprising result because I sincerely thought that I have made progress in SC.
In the four stages, my accuracy rate is 100 percent in the first stage, and the inaccuracy rate fluctuated in the following stages--43%, 29% and 62%. The average difficulty of questions that I answered incorrectly was the highest in the second stage, lowered a bit in the third stage and rose a bit in the final stage from the third stage. Overall, the difficulty of questions I answered incorrectly was higher than the question I answered correctly--so I guess I did not make careless mistakes.
But time pacing is a big problem. The average time per response totaled 2:10, 2:15, 1:52 in the first three stages respectively, but plunged to 0:22 in the final stage! Does it mean that I actually only got about three minutes for the last nine questions?

(Strangely, I remembered that I had more time.)
I am not sure whether my worse performance in RC and SC sectors has something to do with the fact that the last set of nine questions comprises mainly of RC and SC questions (I rushed in the final stage.)
But I am sure that time pacing is a big problem.... In fact I had this pacing problem in all of my previous attempts, but I did not seriously research time pacing skills because I thought that the most effective way is to boost my skills so that I could handle questions more efficiently, as it does not require any pacing skills to handle easy algebra in 62 minutes. I only used one time pacing principle--no question deserves more than three minutes. But now I see that since this test is adaptive testing, there are always questions beyond my reach. So, if I am to retake the test, I would research more into this field.
Thank you experts for your all responses once again!
I have not decided whether to retake GMAT--I really want to try again but I cannot do so in the near term because of the rules regarding limited attempts. Meanwhile, I have not taken the TOEFL test, so I need to take the test first for my applications. Anyway, GMAT is challenging but also enlightens me in so many ways...I will stay at this forum and keep upgrading my verbal skills. I think I might continue seeking your help for some official questions.
AndrewN
Hello again, GraceSCKao. First off, congratulations on crossing the 700 threshold, as well as earning that 50 in Quant. Before I discuss Verbal, I would ask you to consider what you did for Quant, both in terms of preparation and during the exam. My guess is that you loosened up and told yourself that a 50 was within your wheelhouse, and you were able to focus on the question in front of you, one at a time. Perhaps in Verbal, though, you wanted to be careful, spending a little extra time to be sure of your answer. Such a small change on test day is common, but often backfires.
Test-takers run into trouble with the clock, nerves increase, and the combination leads to wild guessing and a decrease in performance. You will probably need to practice more CR questions to gain confidence in your approach. It is often not too hard to whittle down the answer choices to a 50/50, but it is what you do in this situation that separates your best performance from your worst (in CR). You may have to work on selecting the safer option, the one that falls more in line with the logic and information from the passage. Many people chase reasonable-sounding answers in practice and on test day because they have not taken the time to grasp the straight-arrow logic that the passage presents, or they fail to stick to what the question is asking. With practice (and in-house guidance, as needed), you should be able to turn a weakness into a strength by the next time you would choose to sit in the hot seat.
Thank you for the kind words. Indeed, you are not alone in your preparation journey. - Andrew
Thank you
AndrewN for your warm responses!
Since I do not need to use many math skills in my work--I sometimes need to calculate percentage rates but do not use most quant concepts such as prime numbers, factor, divisibility, geometry, algebra and possibilities--I knew that I should work on quant everyday to keep myself exposed to math, and I did so. Over the past six months, I practiced quant for about 1.5 to two hours everyday. In the real test, I was nervous because generally questions are harder than those in the practice exams, but at least I knew what the questions were testing and I had a direction.
I actually spent about the same amount of time on verbal everyday during this period, but mainly on expanding my vocabulary and improving my SC skills. Overall, to be honest, I did not spend as much time on CR or RC as on SC.
In retrospect, I think that I made several incorrect choices between the final two options in those puzzling CR questions. The options I picked might not be the "safer" one or the one that are more in line with the logic, as you said. But even now, I cannot articulate why they are inferior though I've reviewed them a few times in my mind. These selections might reflect a big weak area in my critical thinking.
IanStewart
Congratulations on crossing the 700 threshold, and on your great Quant score! I'm sorry to hear that your Verbal dropped on test day, but if you scored V41-V42 on three unfamiliar official tests, that's your Verbal level. It's very hard to improve on high Verbal scores (there aren't any prep products that help at that level), so if you were able to improve from V38 to that level on your own, you've done very well. Because your Verbal scores were so consistent on your practice tests, it's likely you performed a bit differently on test day.
If there are times of day when you're sharper, you should account for that if you retake (I'm the same way -- I'd probably get a 320 if I took the test too early in the morning). The test is a lot about clear thinking, so these kinds of things can be important. It seems also that you got down to 50-50 on several questions, which happens a lot on harder questions, and when it does, since you end up guessing, your score will be subject to a lot of variance. It's very possible you were just unlucky with a lot of those guesses, and with different luck your score might have been much higher.
But it sounds like the biggest issue may have been pacing, and if you paced yourself differently on this test than on others, that might account for the score drop. It sounds like you probably needed to make some guesses or rushed answers at the end, and in that case it can be hard to get an elite Verbal score. Verbal pacing is not an easy thing to improve at, and if it's something you need to work on, it might be a good idea to ask Verbal teachers on this forum if they have any advice. But I'd bet, from your diagnostics, that if you could retake the test tomorrow, your Verbal score would be a few points higher, assuming you perform as you normally do, and if you'd like to raise your Verbal score, I think retaking would be a good idea.
Thank you for your warm response and encouragement
IanStewart !
I hoped to find a time slot in the afternoon (I am a night owl), but there was no such slot but only those beginning in the morning. I hope that there will be more choices if I am to retake the test.
In the four practice exams, I also had the pacing problem, but it was not as severe as in the real test. I will work on time pacing.
vv65
Commiserations on the score drop
GraceSCKaoHave you ordered the ESR? With 710 you probably do not need to retake, but the ESR sometimes provides clarity on what caused the drop. That may set your mind at ease a little.
Also, please don't think that "all your efforts are to no avail". As others have explained, nerves and small changes on test day can reduce the score dramatically. The consistent 40+ in practice tests shows that your knowledge and skills have certainly improved.]
Thank you
vv65 for your kind response!
I am frustrated with the outcome but you are right that it is not good to think that all my efforts are pointless. (Though, I still wish that the efforts could be reflected in the real test.) I need to use written English in my work and preparing for GMAT helps me better carry out the tasks in work--I could see the mistakes in writing I could not see in the past, or the logic bugs that I took for granted in the past. That is the beauty of this test I guess.
AjiteshArun
To add to the excellent points made by AndrewN and IanStewart, I'd ask you to get the ESR for this attempt, as suggested by vv65. I don't expect it to be too useful, but it'll answer at least some questions you may otherwise spend a lot of time thinking about. For example, were your mistakes concentrated in the last quarter (seven minutes for the final seven questions), or were they more evenly distributed? And although I can't say why your verbal score dropped, the issues you identified (taking the test at a different time, spending more time than you normally would on some questions, and problems managing time) are important (and common) causes of score drops.
It's clear from your posts that you think deeply about and try your best to understand the concepts tested on the GMAT. That's a great quality to have regardless of whether you decide to retake.
Thank you
AjiteshArun for your advice and commendation!
I always learn a lot from your posts and explanations. It is your posts and other experts' that help me try to think deeply about the concepts. Thank you.