diff --git a/backend/pkg/usecases/swipe_manager/interval_logic.go b/backend/pkg/usecases/swipe_manager/interval_logic.go
index e3419fb..0abe9c7 100644
--- a/backend/pkg/usecases/swipe_manager/interval_logic.go
+++ b/backend/pkg/usecases/swipe_manager/interval_logic.go
@@ -34,9 +34,15 @@ func (il *intervalLogic) UpdateInterval(card *repository.Card, swipe *repository
 	card.ReviewDate = time.Now().AddDate(0, 0, card.IntervalDays)
 }
 
-// increaseInterval advances the current interval to the next step.
 func (il *intervalLogic) increaseInterval(card *repository.Card) {
 	currentIndex := il.findIntervalIndex(card.IntervalDays)
+
+	// Check if the current interval is out of the expected range and reset if necessary
+	if currentIndex == 0 && card.IntervalDays != il.intervals[0] {
+		card.IntervalDays = il.intervals[0]
+		return
+	}
+
 	if currentIndex < len(il.intervals)-1 {
 		card.IntervalDays = il.intervals[currentIndex+1]
 	} else {
diff --git a/backend/pkg/usecases/swipe_manager/interval_logic_test.go b/backend/pkg/usecases/swipe_manager/interval_logic_test.go
index 9442f5b..0580604 100644
--- a/backend/pkg/usecases/swipe_manager/interval_logic_test.go
+++ b/backend/pkg/usecases/swipe_manager/interval_logic_test.go
@@ -11,6 +11,7 @@ func TestIncreaseInterval(t *testing.T) {
 	il := NewIntervalLogic().(*intervalLogic)
 
 	t.Run("Normal Range Value 1 to 3", func(t *testing.T) {
+		t.Parallel()
 		card := &repository.Card{IntervalDays: 1}
 		il.increaseInterval(card)
 		if card.IntervalDays != 3 {
@@ -19,6 +20,7 @@ func TestIncreaseInterval(t *testing.T) {
 	})
 
 	t.Run("Normal Range Value 3 to 7", func(t *testing.T) {
+		t.Parallel()
 		card := &repository.Card{IntervalDays: 3}
 		il.increaseInterval(card)
 		if card.IntervalDays != 7 {
@@ -27,6 +29,7 @@ func TestIncreaseInterval(t *testing.T) {
 	})
 
 	t.Run("Edge Case: Max Interval", func(t *testing.T) {
+		t.Parallel()
 		card := &repository.Card{IntervalDays: 30}
 		il.increaseInterval(card)
 		if card.IntervalDays != 30 {
@@ -35,6 +38,7 @@ func TestIncreaseInterval(t *testing.T) {
 	})
 
 	t.Run("Abnormal Range Value", func(t *testing.T) {
+		t.Parallel()
 		card := &repository.Card{IntervalDays: 100}
 		il.increaseInterval(card)
 		if card.IntervalDays != 1 {
@@ -48,6 +52,7 @@ func TestUpdateInterval(t *testing.T) {
 	card := &repository.Card{IntervalDays: 1}
 
 	t.Run("Normal Value with Direction Known", func(t *testing.T) {
+		t.Parallel()
 		swipe := &repository.SwipeRecord{Direction: services.KNOWN}
 		il.UpdateInterval(card, swipe)
 		expectedDate := time.Now().AddDate(0, 0, 3) // because interval should increase to 3
@@ -57,6 +62,7 @@ func TestUpdateInterval(t *testing.T) {
 	})
 
 	t.Run("Reset Interval with Unknown Direction", func(t *testing.T) {
+		t.Parallel()
 		swipe := &repository.SwipeRecord{Direction: services.DONTKNOW}
 		il.UpdateInterval(card, swipe)
 		expectedDate := time.Now().AddDate(0, 0, 1) // reset to 1 day
@@ -66,6 +72,7 @@ func TestUpdateInterval(t *testing.T) {
 	})
 
 	t.Run("Edge Case with Maxed Out Interval", func(t *testing.T) {
+		t.Parallel()
 		card.IntervalDays = 30
 		swipe := &repository.SwipeRecord{Direction: services.KNOWN}
 		il.UpdateInterval(card, swipe)
@@ -80,6 +87,7 @@ func TestFindIntervalIndex(t *testing.T) {
 	il := NewIntervalLogic().(*intervalLogic)
 
 	t.Run("Find Index for Interval 1", func(t *testing.T) {
+		t.Parallel()
 		index := il.findIntervalIndex(1)
 		if index != 0 {
 			t.Errorf("Expected index to be 0, got %d", index)
@@ -87,6 +95,7 @@ func TestFindIntervalIndex(t *testing.T) {
 	})
 
 	t.Run("Find Index for Interval 7", func(t *testing.T) {
+		t.Parallel()
 		index := il.findIntervalIndex(7)
 		if index != 2 {
 			t.Errorf("Expected index to be 2, got %d", index)
@@ -94,6 +103,7 @@ func TestFindIntervalIndex(t *testing.T) {
 	})
 
 	t.Run("Find Index for Abnormal Interval", func(t *testing.T) {
+		t.Parallel()
 		index := il.findIntervalIndex(100)
 		if index != 0 {
 			t.Errorf("Expected index to be 0 for abnormal value, got %d", index)