Here's a bit more information that might be helpful:
QUESTION 1: "Is the quiz still accessible to the student after the time limit + grace period expires?"
ANSWER: Yes -- it's still there because there's no way for D2L to, in effect, "take it away" once it's downloaded to the user's local browser page.
QUESTION 2: "So, theoretically, students could continue trying to take the quiz and answer questions after the time limit is up, and the only way the instructor would know this is by checking each individual record?"
ANSWER: Students can continue to answer questions, but they cannot save their answers. Any unsaved answers will not be recorded -- so even if the instructor checked each individual record, they will not see the unsaved/unrecorded answers. Those will be blank.
With the "auto-submit" selection, the quiz behaves this way:
- student is able to save the answers to questions as they go along UNTIL time + grace period has expired
- if the student continues to answer questions AFTER the time + grace has expired, they will get no notification UNTIL they attempt to SAVE or SUBMIT QUIZ
- if the student attempts to save answers after the time + grace has expired, they will see a popup message that says "Time Limit Exceeded - The time limit for this quiz has been exceeded, please submit your quiz." ... THESE ANSWERS ARE NOT SAVED, even though the student still needs to click "submit quiz"
- because the answers will not be saved to the system, the answer will be recorded as a blank, and the quiz attempt will score those unsaved answers as "0"
QUESTION 3: "Will my students get warnings and flags for quizzes submitted 30 seconds late, etc.--amounts of time that are really not important?"
ANSWER: The student gets a warning, as described above, each time they attempt to save an answer after the time+grace has expired. D2L doesn't differentiate between "important" or "unimportant" periods of time -- the grace period is designed to cover that kind of "leeway." The student doesn't get any flags when submitting the quiz late, but the instructor will see a red flag for any quiz submitted late, whether 30 seconds or 30 days.