I do not understand why it shows a user the correct answers to a quiz that they're allowed to take over? There's really no reason to do a do-over if you're given the answers one minute prior. I think it should only show solutions on the last take if any other takes resulted in a failed percentage. Or maybe do some time frame in between takes, or at least give us a setting that allows us to turn it on only for the last take. Another thought could be, ask the user to confirm when they want to see results as long as they understand they wont be able to take it again after they look at the results.
This is an amazing module, you've done a ton of great work. I'm blown away at how powerful it it - thank you!