I decided to apply to Business school 3 months before the application was due. I knew that I wouldn't have time to take the GMAT multiple times and had to ensure the my studying was as efficient as possible. The Economist GMAT course exceeded my expectations. The lessons were concise and easy to understand, and the one-on-one tutoring sessions were extremely valuable.
The best part about the course are all of the practice problems. When you get a question wrong, it not only tells you what the correct answer is, but also why the answer you selected is wrong. You have the opportunity to send an "ask a tutor" inquiry if there are questions that you still don't understand after reading the explanation. I ended up only needing to use about 20 out of 50 available "ask a tutor" inquiries because the explanations provided are so thorough.
After completing the Economist GMAT Prep Course in 2.5 months, I improved my score by 130 points and achieved my target score of 720. I highly recommend the Economist GMAT course!