airquiz results are e-mailed back <2 mins of submitting the exam. I only tend to do a couple of exams a day, the rest of the time it's checking the questions I've got wrong, and trying to understand why I had failed them. It can take some time to research and I usually 'read around' the subject to get a big picture, just in case it's more of a complicated issue that I have not grasped.
Lots of what you will learn you will either forget or never use, but don't let this put you off. Your PPL is a license to learn, the exams just make sure you know the required knowledge at that particular time to get your license.
IMHO learning to fly is not done by passing exams - it's by flying.