At the beginning of a quiz the user is told twice how many attempts they are allowed, but is never told the consequences of those attempts. It's not until after the first attempt that some users realize they're penalized for an incorrect first guess. No user understood why they were allowed to make attempts which resulted in no marks (e.g., a third attempt).
Why it matters
Quizzes affect users' grades, something they care about very much. Moodle should be explicit about how those grades are calculated so users can make the best possible decisions about how to take the quiz.
On the quiz summary page, instead of text like this:
Attempts allowed: 2
Grading method: Last attempt
Moodle should be explicit and more verbose about what exactly that means.