Excellent for Sentence Correction

I took GMAT in February 2018 and scored a 660 (Q47 and V34). I had made the fatal mistake of looking at the official verbal questions only in the last week before the exam. The official questions were quite different from the ones I had seen earlier from another test prep company.

I bought the ESR to find out how i did across the three sub-sections in verbal. The ESR showed that I scored in the 97% percentile in critical reasoning, 78th percentile in reading comprehension, and 39th percentile in sentence correction.

To improve my sentence correction skills, I enrolled in e-GMAT's verbal online course since I had read some great reviews about this course on GMAT club. I covered all their sentence correction modules and took all the practice tests they provided.

After that I attempted all questions in the Official guide and Official verbal guide. My accuracy was nearly 85%. I took the GMAT again in Dec 2018 and scored 720 (Q48, V41). In this attempt I scored in the 91st percentile in both critical reasoning and sentence correction and in the 88th percentile in reading comprehension.

I would attribute the increase in the sentence correction score from 39th to 91st percentile to just two resources:

1) e-GMAT's verbal online course.
2) Official GMAT questions.

For reading comprehension, I just relied on doing more official questions.

For anyone wanting to improve their verbal score, especially sentence correction, e-GMAT's verbal online course seems to be the best option so far.