I wanted to share my GMAT story as I've been a huge beneficiary of this site and community. The synthesis here is that I actually didn't improve on my sight-unseen first practice test after a couple of weeks of prep, though I feel like the prep was still valuable for reducing risk and giving me a shot perhaps at a higher upside.
This isn't a rags to riches story; though perhaps there's something in here of use. First prep - 2009
In late 2009 I decided to start prepping for the GMAT and found this site, did some pre-reading on test structure, format etc but quickly work got in the way before I'd logged even 10 hours of prep.
What I did get done in that time:
* Downloaded the official software
* Took the first official practice test (after ~2 hours of familiarisation with question types)
* Began to understand where I'd be weak and strong
On the first test I got 740; which in retrospect turned out to be somewhat outside my ability. Sorry can't remember the split. My initial back-of-the-envelope diagnostic was that I was pretty even across both Q and V, though within Q I'd need to work on number theory as a topic, and (probably like most people), data sufficiency as a question format. For verbal I needed to improve sentence correction.
I never intended to make applications until 2012 anyway, so once work heated up the prep dried up completely. 2nd round; Christmas 2011
This time I pre-booked the test 18 days ahead, and decided to just make a run at it. My prep routine was basically get up, drink a coffee and then sit down for a solid 3 hours in the morning, with an additional hour in the evening to review questions I'd gotten wrong etc. I did this each weekday (for 12 weekdays I think).
This time I was more structured:
* Bought Kaplan
* Downloaded GMAT CLUB iPad app
I can't stress enough how useful I found the iPad app. I've always been someone who learned by doing; being able to crunch through hundreds (over 500 practice questions complete by the time I did the test) of questions enabled me to learn much of what I needed, and importantly not get bored out of my brain by trying to review the same slabs of text over and over again.
A few things stood out for me as being important in my prep - these may or may not apply to you, but for what it's worth:
* Identify early where you're weak - this will be your area of greatest return on effort from study
* Find questions of the right level of difficulty to practice; this is important - the GMAT puts you on the margin deliberately in terms of your ability to answer correctly...you should be trying to push out this frontier all the time, which means not practicing easy questions which don't challenge you...but also not attempting questions which you're unlikely to face many of in the real test due to level of difficulty
* Be disciplined in using the above two criteria to prioritise the questions you practice
* Where you get something wrong, identify the theory. But actually, really, identify the theory. Not "oh I can see why the OA suggests that". I mean "I am now confident that not only would I get the same answer as OA on this question", but "using the same logical process I would get the correct answer on any analagous question
* DS questions in particularly are a double test - they test format logic and topic mastery. By format logic I mean, "is this candidate able to understand the implications of different proofs and their interactions". By topic mastery I just mean "does this candidate know the [insert boring maths rule/concept here]". Practice these two bits separately; it'll be very hard to practice the first in an area where you're weak on the second
* SC provides an opportunity to save minutes; prep here should focus not only on getting correct answer but getting it fast. This is a heuristic exercise- there's almost always a correct answer that you can get to quite quickly by applying the right filters/tests to the options...not much "weighing up" to do - which is what you want to be spending you time on in other questions
2 days before my final test I did the 2nd official practice test...and scored 740 again.The test
On test day the only notable thing to happen was that the original marker they gave me to write on the transparency didn't work...nor did the replacement, meaning the first 10 mins of my Q section I couldn't make notes. To be honest I don't think this made a big difference to my answers, though stressed me out somewhat. I ended up finishing with 2-3 minutes to spare, having guessed 2 questions.
Verbal felt quite easy - I finished with a full 10 minutes to spare having slowed down a lot when I was beating the clock at the half way mark.
My split was 80th percentile Q and 97th percentile V, for an overall of 730. This was different from my practice tests where I'd been 90th (approx) in both. I think I had a bad day in Q - it happens - and in verbal I probably took more time to answer questions than I usually did in practice, giving me a better result.Conclusion
My takeaways are:
* iPad app great
* GMAT Club great
* Hard to improve scores once you're in the 700s; probably takes more than 20-30 hours of prep to really move the needle