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.
Taking the Gmat is a very big event as it does limit or expand your opportunities to advance into business schools. There are options to re-take the Gmat if the first score is not where the students would like it to be. Study, review and taking courses on writing the exam are all important to raise the score.