I found recently that if an user creates quiz in frontend and did not complete it by pressing finish button, but just leave the page, there is no way to get back to that quiz, as it doesnt appear in users quiz

also incomplete quizzes are not registered in the backend so there is no way for admin to know that incomplete quizzes are there.

the quizzes must be listed at both end, so that a returning user can complete the quiz at later time and also at back end so that an admin can send a reminder for a user to complete a quiz, or this process can be automated in for of automatic reminders.