Hi, I'm sorry that you've waited so long for a reply! For some reason, your post didn't show up for me the last time I was on. And I'm sorry that you had trouble posting in the first place!
There are various reasons why someone's score could decline—though I will say that a difference of 20-30 points isn't really a decline. I would call that "stagnating." You lifted your score into the low-to-mid-500 range (good job!) but now you are just staying in the same place—so we have to figure out how to get you unstuck and climbing again.
First, you said you took our course. When did the course end? Did you use your Post-Course Assessment (the 30-minute online meeting with an instructor to go over the data from the CATs you took during the course and to come up with a post-course study plan)?
If so, give me an overall summary of what the instructor told you. If not, and if it has not been too long since your course, sign up for the PCA now. If you're still within 30 days of the last day of your course, you can sign up yourself in Atlas. Look under Course Information and then PCA/Office Hours. (PCA stands for Post-Course Assessment.) If it has been more than 30 days, you can contact our student services team to see whether you can get an extension to do it now. (If it's only a few weeks longer, you can usually get an extension. If it's been months since your course ended, they may not be able to make an exception.)
Next, the two major culprits at this stage (when someone's score stops going up) are usually some combination of time management and test anxiety. One common scenario: You learn a bunch of stuff / you can do more than you used to be able to do. So naturally you try to do more when you take a test—but you actually try to do too much and then mess up your timing and then your score drops. The GMAT is a "where you end is what you get" test—your scoring level at the end of each section (for Q and V) is your score for that section. So if you mess up the timing and your score drops by the end...well, where you end is what you get.
And of course, you get anxious when you realize that your timing is messed up, which makes it harder to concentrate, and that leads to more careless mistakes, ... and so it just all spirals together into a very frustrating test experience.
I just peaked at your test data for your last CAT and timing is definitely a big issue. On both sections, go look at your scoring trajectory. Your ending point for the section is about 20 percentile points lower than your peak for Verbal and even more than that for Quant—you're basically lifting (but taking too much time to lift that high) and then dropping. Since your score isn't an average of your performance across the section but just a reflection of where you end, that's why your score keeps staying in the same range.
There's a good chance that you already have the content knowledge that you need to get your goal score of 610. What you need to concentrate on now is
how to take this test—and that means improving your executive reasoning / decision-making skills.
Read this (right now, before you keep reading the rest of my post):
https://www.manhattanprep.com/gmat/blog ... lly-tests/Do you see how what you're doing doesn't fit with what that post says? You're prioritizing getting stuff right over timing, but the GMAT wants you to balance those two goals. There are trade-offs between timing and getting stuff right, and you have to make good "business" decisions about when to prioritize one over the other. If you always prioritize getting stuff right, you won't be able to keep lifting your score on the GMAT.
Now, go read this (or watch the webinar linked at the beginning of the article, your choice):
https://www.manhattanprep.com/gmat/blog ... -the-gmat/Then come back here and tell me what you think you need to do in order to develop that business mindset for the GMAT. (I'll tell you what I think, too—but the act of thinking about what you need to do for yourself will help you to get into the business mindset better than if I just tell you. So you tell me first what you think.)
Here's a resource to help you specifically with time management:
blog/2016/08/19/everything-you-need-to-know-about-gmat-time-management-part-1-of-3/Finally, go back into your most recent test or two and analyze your decision-making. Where did you make decisions that you think were good ones? Where do you think you should have made different decisions? Why should you have made those different decisions, and what should have been the trigger? (Then you'll know how and when to make those better decisions next time.)
In particular, analyze the decisions you made on the questions on which you spent too much time. For example, on quant, you spent a little over 20 minutes (almost 1/3 of your total time) on 5 questions! You got 2 right and 3 wrong. You then missed *9* questions in a row at the end because you were running out of time.
If you had gotten all 5 of those other questions wrong in 1 min each (that is, if you'd chosen to bail on them—even the ones you ended up getting right!), you would have had more than 15 minutes extra to spend at the end of the section. And that might have helped you to avoid the end-of-section drop that killed your score.
Then come back and tell me what you think.
Sorry for this laaate response, got the flu…