Hi FreakingGPAforZero,
There are a number of different issues to discuss, so I'm going to work through your answers in order:
To start, studying for the GMAT is probably unlike the type(s) of studying that you've done before. This process requires a larger, more consistent study routine than most people are used to (including studying throughout the week instead of 'cramming'). Oftentimes, a commitment of 10-15 hours per week (or more) over the course of 3 months (or more) is what's required to build the necessary skills to score at a high level. While there are exceptions, many Test Takers end up studying far more than they originally thought they would have to. Studying just 4 hours a week wouldn't have allowed you to do too much or really hone too many skills. While you've clearly made some nice improvements so far, a significant change in your routine will be necessary.
Many Test Takers who use a "book heavy" study approach end up getting 'stuck' at a particular scoring level. The
OG books are great sources for practice questions, but they're not designed to teach you Tactics, patterns or any of the 'secrets' to the GMAT. Even the best Course books are limited in what they can teach you; they also can't force you to approach questions in a certain way and their explanations are often one-sided. This is meant to say that you'll likely need to invest in some new non-book resources.
A 780 is not a realistic goal. Thankfully, you won't find any Schools that 'require' a score that high. You have to remember the REAL goal in all of this: to get into your first-choice Business School. Thus, you need a competitive GMAT score, a strong OVERALL profile AND you need to properly 'market yourself' to each of the Schools that you plan to apply to.
Based on your timeline, you've given yourself plenty of time to study and work on your applications, so you've made some good choices already. Now you have to make some new choices regarding your studies going forward.
1) What Schools are you planning to apply to?
2) How many hours could you commit to studying each week?
GMAT assassins aren't born, they're made,
Rich