diff --git a/studies.py b/studies.py
index 069c3e084..4d233f464 100644
--- a/studies.py
+++ b/studies.py
@@ -351,9 +351,9 @@ def objective_timeline(trial: optuna.Trial) -> float:
         ),
         storage=storage,
     )
-    study.enqueue_trial({"x": 0.9})
-    study.enqueue_trial({"x": 0.5})
-    study.enqueue_trial({"x": 0.3})
+    study.enqueue_trial({"x": 0.9})  # Add a FAIL trial.
+    study.enqueue_trial({"x": 0.5})  # Add a PRUNED trial.
+    study.enqueue_trial({"x": 0.3})  # Add a COMPLETE trial.
     study.optimize(objective_timeline, n_trials=50, n_jobs=2, catch=(ValueError,))
     studies.append((study.study_name, study))