diff --git a/internal/pkg/calendar/calendar.go b/internal/pkg/calendar/calendar.go
index ab301e51..2afd0379 100644
--- a/internal/pkg/calendar/calendar.go
+++ b/internal/pkg/calendar/calendar.go
@@ -89,54 +89,32 @@ func RandomTimeInRange(mtbf string, startHour int, endHour int, loc *time.Locati
 		return []time.Time{time.Now().Add(time.Duration(24*365*10) * time.Hour)}
 	}
 
-	one_day, _ := time.ParseDuration("24h")
+	startTime := time.Now().In(loc)
 
-	// If the mtbf is bigger or equal to one day we will calculate one
-	// random time in the range. If not we will calculate several random
-	// times.
-	if tmptimeDuration >= one_day {
-		// calculate the number of minutes in the range
-		minutesInRange := (endHour - startHour) * 60
-
-		// calculate a random minute-offset in range [0, minutesInRange)
+	for {
+		//time range should be twice of the input mean time between failure value
+		timeDuration := tmptimeDuration * 2
+		//compute random offset time
+		mtbfEndTime := startTime.Add(timeDuration)
+		subSecond := int64(mtbfEndTime.Sub(startTime) / time.Second)
 		r := rand.New(rand.NewSource(time.Now().UnixNano()))
-		randMinuteOffset := r.Intn(minutesInRange)
-		offsetDuration := time.Duration(randMinuteOffset) * time.Minute
-
-		// Add the minute offset to the start of the range to get a random
-		// time within the range
-		year, month, date := time.Now().Date()
-		rangeStart := time.Date(year, month, date, startHour, 0, 0, 0, loc)
-		times = append(times, rangeStart.Add(offsetDuration))
-		return times
-	} else {
-		startTime := time.Now().In(loc)
-
-		for {
-			//time range should be twice of the input mean time between failure value
-			timeDuration := tmptimeDuration * 2
-			//compute random offset time
-			mtbfEndTime := startTime.Add(timeDuration)
-			subSecond := int64(mtbfEndTime.Sub(startTime) / time.Second)
-			r := rand.New(rand.NewSource(time.Now().UnixNano()))
-			randSecondOffset := r.Int63n(subSecond)
-			randCalTime := startTime.Add(time.Duration(randSecondOffset) * time.Second)
-
-			// compute randSecondOffset between start and end hour
-			year, month, date := startTime.Date()
-			todayEndTime := time.Date(year, month, date, endHour, 0, 0, 0, loc)
-			todayStartTime := time.Date(year, month, date, startHour, 0, 0, 0, loc)
-			if startTime.Before(todayStartTime) { // now is earlier then start hour, only for test pass, normal process won't run into this condition
-				return []time.Time{todayStartTime}
-			}
-			if randCalTime.Before(todayEndTime) { // time offset before today's endHour
-				glog.V(1).Infof("RandomTimeInRange calculate time %s", randCalTime)
-				times = append(times, randCalTime)
-				// Move start time up to the calculated random time
-				startTime = randCalTime
-			} else {
-				return times
-			}
+		randSecondOffset := r.Int63n(subSecond)
+		randCalTime := startTime.Add(time.Duration(randSecondOffset) * time.Second)
+
+		// compute randSecondOffset between start and end hour
+		year, month, date := startTime.Date()
+		todayEndTime := time.Date(year, month, date, endHour, 0, 0, 0, loc)
+		todayStartTime := time.Date(year, month, date, startHour, 0, 0, 0, loc)
+		if startTime.Before(todayStartTime) { // now is earlier then start hour, only for test pass, normal process won't run into this condition
+			return []time.Time{todayStartTime}
+		}
+		if randCalTime.Before(todayEndTime) { // time offset before today's endHour
+			glog.V(1).Infof("RandomTimeInRange calculate time %s", randCalTime)
+			times = append(times, randCalTime)
+			// Move start time up to the calculated random time
+			startTime = randCalTime
+		} else {
+			return times
 		}
 	}
 }
diff --git a/internal/pkg/schedule/schedule.go b/internal/pkg/schedule/schedule.go
index 69d84baf..62354797 100644
--- a/internal/pkg/schedule/schedule.go
+++ b/internal/pkg/schedule/schedule.go
@@ -81,20 +81,9 @@ func New() (*Schedule, error) {
 	}
 
 	for _, victim := range victims {
-		mtbf := victim.Mtbf()
-		parsed_mtbf, err := calendar.ParseMtbf(mtbf)
-		if err != nil {
-			glog.Errorf("error parsing customized mtbf for %s/%s in namespace %s - %s: %v", victim.Kind(), victim.Name(), victim.Namespace(), mtbf, err)
-			continue
-		}
-		killtimes := CalculateKillTimes(mtbf)
-		one_day, _ := time.ParseDuration("24h")
-		// If the parsed mtbf value is less than one day we want to add the calculated kill times no matter
-		// what and otherwise we use probability to decide if we will schedule the calculated kill time.
-		if parsed_mtbf < one_day || ShouldScheduleChaos(float64(parsed_mtbf / one_day)) {
-			for _, killtime := range killtimes {
-				schedule.Add(chaos.New(killtime, victim))
-			}
+		killtimes := CalculateKillTimes(victim.Mtbf())
+		for _, killtime := range killtimes {
+			schedule.Add(chaos.New(killtime, victim))
 		}
 	}
 
@@ -111,13 +100,3 @@ func CalculateKillTimes(mtbf string) []time.Time {
 	}
 	return calendar.RandomTimeInRange(mtbf, config.StartHour(), config.EndHour(), loc)
 }
-
-func ShouldScheduleChaos(mtbf float64) bool {
-	if config.DebugEnabled() && config.DebugForceShouldKill() {
-		return true
-	}
-
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	probability := 1 / mtbf
-	return probability > r.Float64()
-}
diff --git a/internal/pkg/schedule/schedule_test.go b/internal/pkg/schedule/schedule_test.go
index 3af46394..c8ac6f41 100644
--- a/internal/pkg/schedule/schedule_test.go
+++ b/internal/pkg/schedule/schedule_test.go
@@ -111,16 +111,3 @@ func TestCalculateKillTimeNow(t *testing.T) {
 	assert.WithinDuration(t, killtimes[0], time.Now(), time.Second*time.Duration(60))
 	config.SetDefaults()
 }
-
-func TestShouldScheduleChaosNow(t *testing.T) {
-	config.SetDefaults()
-	viper.SetDefault(param.DebugEnabled, true)
-	viper.SetDefault(param.DebugForceShouldKill, true)
-	assert.True(t, ShouldScheduleChaos(100000000000))
-	config.SetDefaults()
-}
-
-func TestShouldScheduleChaosMtbf(t *testing.T) {
-	assert.False(t, ShouldScheduleChaos(100000000000))
-	assert.True(t, ShouldScheduleChaos(1))
-}