diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 286f7e2a205..3167387ade9 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -9307,6 +9307,25 @@ function mtrace($string, $eol="\n", $sleep=0) {
     }
 }
 
+/**
+ * Helper to {@see mtrace()} an exception or throwable, including all relevant information.
+ *
+ * @param Throwable $e the error to ouptput.
+ */
+function mtrace_exception(Throwable $e): void {
+    $info = get_exception_info($e);
+
+    $message = $info->message;
+    if ($info->debuginfo) {
+        $message .= "\n\n" . $info->debuginfo;
+    }
+    if ($info->backtrace) {
+        $message .= "\n\n" . format_backtrace($info->backtrace, true);
+    }
+
+    mtrace($message);
+}
+
 /**
  * Replace 1 or more slashes or backslashes to 1 slash
  *
diff --git a/lib/setuplib.php b/lib/setuplib.php
index 5bff47a54e2..10e002a89bb 100644
--- a/lib/setuplib.php
+++ b/lib/setuplib.php
@@ -482,11 +482,12 @@ function is_early_init($backtrace) {
 
 /**
  * Returns detailed information about specified exception.
- * @param exception $ex
- * @return object
+ *
+ * @param Throwable $ex any sort of exception or throwable.
+ * @return stdClass standardised info to display. Fields are clear if you look at the end of this function.
  */
-function get_exception_info($ex) {
-    global $CFG, $DB, $SESSION;
+function get_exception_info($ex): stdClass {
+    global $CFG;
 
     if ($ex instanceof moodle_exception) {
         $errorcode = $ex->errorcode;
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 5ffd7bdcf55..56785a27cae 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -18,6 +18,7 @@ information provided here is intended especially for developers.
   It only worked with http sites and did not officially support SSL, and is at risk of disappearing should Yahoo! decide
   to remove it.
 * New `properties_filter` method of persistent class for filtering properties of a record against persistent definition
+* There is a new helper function mtrace_exception to help with reporting exceptions you have caught in scheduled tasks.
 
 === 4.1 ===
 
diff --git a/mod/quiz/report/statistics/classes/task/recalculate.php b/mod/quiz/report/statistics/classes/task/recalculate.php
index 6d5906be865..4d59537f0e6 100644
--- a/mod/quiz/report/statistics/classes/task/recalculate.php
+++ b/mod/quiz/report/statistics/classes/task/recalculate.php
@@ -36,21 +36,33 @@ require_once($CFG->dirroot . '/mod/quiz/report/statistics/report.php');
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class recalculate extends \core\task\scheduled_task {
+    /** @var int the maximum length of time one instance of this task will run. */
+    const TIME_LIMIT = 3600;
 
-    public function get_name() {
+    public function get_name(): string {
         return get_string('recalculatetask', 'quiz_statistics');
     }
 
-    public function execute() {
+    public function execute(): void {
         global $DB;
+        $stoptime = time() + self::TIME_LIMIT;
+        $dateformat = get_string('strftimedatetimeshortaccurate', 'core_langconfig');
+
         // TODO: MDL-75197, add quizid in quiz_statistics so that it is simpler to find quizzes for stats calculation.
         // Only calculate stats for quizzes which have recently finished attempt.
         $sql = "
-            SELECT qa.quiz, MAX(qa.timefinish) as timefinish
+            SELECT q.id AS quizid,
+                   q.name AS quizname,
+                   c.id AS courseid,
+                   c.shortname AS courseshortname,
+                   MAX(qa.timefinish) AS mostrecentattempttime,
+                   COUNT(1) AS numberofattempts
               FROM {quiz_attempts} qa
+              JOIN {quiz} q ON q.id = qa.quiz
+              JOIN {course} c ON c.id = q.course
              WHERE qa.preview = 0
                AND qa.state = :quizstatefinished
-          GROUP BY qa.quiz
+          GROUP BY q.id, q.name, c.id, c.shortname
         ";
 
         $params = [
@@ -59,30 +71,50 @@ class recalculate extends \core\task\scheduled_task {
 
         $latestattempts = $DB->get_records_sql($sql, $params);
 
+        $anyexception = null;
         foreach ($latestattempts as $attempt) {
-            $quizobj = quiz::create($attempt->quiz);
+            if (time() >= $stoptime) {
+                mtrace("This task has been running for more than " .
+                        format_time(self::TIME_LIMIT) . " so stopping this execution.");
+                break;
+            }
+
+            mtrace("  Examining quiz '$attempt->quizname' ($attempt->quizid) in course " .
+                    "$attempt->courseshortname ($attempt->courseid) with most recent attempt at " .
+                    userdate($attempt->mostrecentattempttime, $dateformat) . ".");
+            $quizobj = quiz::create($attempt->quizid);
             $quiz = $quizobj->get_quiz();
             // Hash code for question stats option in question bank.
             $qubaids = quiz_statistics_qubaids_condition($quiz->id, new \core\dml\sql_join(), $quiz->grademethod);
 
             // Check if there is any existing question stats, and it has been calculated after latest quiz attempt.
-            $records = $DB->get_records_select(
-                'quiz_statistics',
-                'hashcode = :hashcode AND timemodified > :timefinish',
-                [
-                    'hashcode' => $qubaids->get_hash_code(),
-                    'timefinish' => $attempt->timefinish
-                ]
-            );
+            $lateststatstime = $DB->get_field('quiz_statistics', 'COALESCE(MAX(timemodified), 0)',
+                    ['hashcode' => $qubaids->get_hash_code()]);
 
-            if (empty($records)) {
+            if ($lateststatstime >= $attempt->mostrecentattempttime) {
+                mtrace("    Statistics already calculated at " . userdate($lateststatstime, $dateformat) .
+                        " so nothing to do for this quiz.");
+                continue;
+            }
+
+            mtrace("    Calculating statistics for $attempt->numberofattempts attempts, starting at " .
+                    userdate(time(), $dateformat) . " ...");
+            try {
                 $report = new quiz_statistics_report();
-                // Clear old cache.
                 $report->clear_cached_data($qubaids);
-                // Calculate new stats.
                 $report->calculate_questions_stats_for_question_bank($quiz->id);
+                mtrace("    Calculations completed at " . userdate(time(), $dateformat) . ".");
+
+            } catch (\Throwable $e) {
+                // We don't want an exception from one quiz to stop processing of other quizzes.
+                mtrace_exception($e);
+                $anyexception = $e;
             }
         }
-        return true;
+
+        if ($anyexception) {
+            // If there was any error, ensure the task fails.
+            throw $anyexception;
+        }
     }
 }