30-40 hours a week? Sounds like a full-time job! If you can allocate 2 full weeks of intense, full-time studying, I would recommend that. Why? Because
consecutive studying will help you easily remember what you studied the day before and internalize the concepts in time for the exam.
For those who can't dedicate
sprint-like periods of study time due to other obligations, try to evaluate yourself. You know best how much time you can allocate to studying and how disciplined you are to sticking with that routine.
If you have extremely good study habits---your undergraduate GPA is strong--and you don't really need a strong GMAT score to balance weak academics, then the
OG and GMAT Prep software alone can be good enough. However, most students will look for additional assistance spread out between at least 1-3 months, usually more.
Paying for classes is like paying for motivation! Keep an eye out for what's out there and choose what fits your study habits best.In any case, I would highly recommend
consecutive studying as opposed to studying only on Saturdays and Sundays and leaving the weekdays empty. Having said that, since many students are on a schedule that is tight during the weekdays, online prep is the way to go. Keep an open mind when considering your available options!