I'd like to add something to Linda's post, just to get the idea out.
I've noticed one quizmaker who is very creative, and has at any given time about 20 new quizzes ready to go online! What he does is he creates them any time he wants and saves them without going online, even when they're finished. Then he just waits until his latest submission has gone through the queue all right and submits the next one.
The submission limit doesn't mean you cant create more than one quiz at a time, only that we ask you to let one quiz go online before submitting another one for editor review.
This clever kid has a continuous cache of quizzes (try saying that 3 times fast!) ready and as a result has been getting a new quiz online every couple of days.
So keep the creative juices flowing, everyone!