One of the keys to good, quality Gmat study time is to learn how to break down the problem into workable and understandable sections. One the problem is understood, arriving at the correct answer will be less challenging. Not correctly analyzing the problem is the biggest cause of low Gmat scores.
For working professionals some Gmat programs offer weekend or evening classes that allow the student to continue working while still having the choice to attend an in person class. There may also be the option to miss or skip a class and make it up at another time if work scheduling conflicts.