diff --git a/src/utils/settingsValidation/__tests__/index.spec.ts b/src/utils/settingsValidation/__tests__/index.spec.ts
index 45e357ce..f2c2431b 100644
--- a/src/utils/settingsValidation/__tests__/index.spec.ts
+++ b/src/utils/settingsValidation/__tests__/index.spec.ts
@@ -53,6 +53,7 @@ describe('settingsValidation', () => {
     }, minimalSettingsParams);
 
     expect(settings.sync.impressionsMode).toBe(OPTIMIZED);
+    expect(settings.scheduler.impressionsRefreshRate).toBe(300000);
   });
 
   test('impressionsMode should be configurable', () => {
@@ -66,6 +67,7 @@ describe('settingsValidation', () => {
     }, minimalSettingsParams);
 
     expect(settings.sync.impressionsMode).toEqual(DEBUG);
+    expect(settings.scheduler.impressionsRefreshRate).toBe(60000); // Different default for DEBUG impressionsMode
   });
 
   test('urls should be configurable', () => {
@@ -247,11 +249,13 @@ describe('settingsValidation', () => {
   test('validate min values', () => {
     const settings = settingsValidation({
       scheduler: {
-        telemetryRefreshRate: 0
+        telemetryRefreshRate: 0,
+        impressionsRefreshRate: 'invalid',
       }
     }, minimalSettingsParams);
 
     expect(settings.scheduler.telemetryRefreshRate).toBe(60000);
+    expect(settings.scheduler.impressionsRefreshRate).toBe(60000);
   });
 
 });
diff --git a/src/utils/settingsValidation/index.ts b/src/utils/settingsValidation/index.ts
index 1d83e2b1..2eca446a 100644
--- a/src/utils/settingsValidation/index.ts
+++ b/src/utils/settingsValidation/index.ts
@@ -1,7 +1,7 @@
 import { merge } from '../lang';
 import { mode } from './mode';
 import { validateSplitFilters } from './splitFilters';
-import { STANDALONE_MODE, OPTIMIZED, LOCALHOST_MODE } from '../constants';
+import { STANDALONE_MODE, OPTIMIZED, LOCALHOST_MODE, DEBUG } from '../constants';
 import { validImpressionsMode } from './impressionsMode';
 import { ISettingsValidationParams } from './types';
 import { ISettings } from '../../types';
@@ -33,8 +33,8 @@ const base = {
     segmentsRefreshRate: 60,
     // publish telemetry stats each 3600 secs (1 hour)
     telemetryRefreshRate: 3600,
-    // publish evaluations each 60 sec
-    impressionsRefreshRate: 60,
+    // publish evaluations each 300 sec (default value for OPTIMIZED impressions mode)
+    impressionsRefreshRate: 300,
     // fetch offline changes each 15 sec
     offlineRefreshRate: 15,
     // publish events every 60 seconds after the first flush
@@ -112,6 +112,9 @@ export function settingsValidation(config: unknown, validationParams: ISettingsV
   const log = logger(withDefaults); // @ts-ignore, modify readonly prop
   withDefaults.log = log;
 
+  // ensure a valid impressionsMode
+  withDefaults.sync.impressionsMode = validImpressionsMode(log, withDefaults.sync.impressionsMode);
+
   function validateMinValue(paramName: string, actualValue: number, minValue: number) {
     if (actualValue >= minValue) return actualValue;
     // actualValue is not a number or is lower than minValue
@@ -123,11 +126,21 @@ export function settingsValidation(config: unknown, validationParams: ISettingsV
   const { scheduler, startup } = withDefaults;
   scheduler.featuresRefreshRate = fromSecondsToMillis(scheduler.featuresRefreshRate);
   scheduler.segmentsRefreshRate = fromSecondsToMillis(scheduler.segmentsRefreshRate);
-  scheduler.impressionsRefreshRate = fromSecondsToMillis(scheduler.impressionsRefreshRate);
   scheduler.offlineRefreshRate = fromSecondsToMillis(scheduler.offlineRefreshRate);
   scheduler.eventsPushRate = fromSecondsToMillis(scheduler.eventsPushRate);
   scheduler.telemetryRefreshRate = fromSecondsToMillis(validateMinValue('telemetryRefreshRate', scheduler.telemetryRefreshRate, 60));
 
+  if (scheduler.impressionsRefreshRate !== base.scheduler.impressionsRefreshRate) {
+    // Validate impressionsRefreshRate defined by user
+    scheduler.impressionsRefreshRate = validateMinValue('impressionsRefreshRate', scheduler.impressionsRefreshRate,
+      withDefaults.sync.impressionsMode === DEBUG ? 1 : 60 // Min is 1 sec for DEBUG and 60 secs for OPTIMIZED
+    );
+  } else {
+    // Default impressionsRefreshRate for DEBUG mode is 60 secs
+    if (withDefaults.sync.impressionsMode === DEBUG) scheduler.impressionsRefreshRate = 60;
+  }
+  scheduler.impressionsRefreshRate = fromSecondsToMillis(scheduler.impressionsRefreshRate);
+
   // Log deprecation for old telemetry param
   if (scheduler.metricsRefreshRate) log.warn('`metricsRefreshRate` will be deprecated soon. For configuring telemetry rates, update `telemetryRefreshRate` value in configs');
 
@@ -189,9 +202,6 @@ export function settingsValidation(config: unknown, validationParams: ISettingsV
   withDefaults.sync.splitFilters = splitFiltersValidation.validFilters;
   withDefaults.sync.__splitFiltersValidation = splitFiltersValidation;
 
-  // ensure a valid impressionsMode
-  withDefaults.sync.impressionsMode = validImpressionsMode(log, withDefaults.sync.impressionsMode);
-
   // ensure a valid user consent value
   // @ts-ignore, modify readonly prop
   withDefaults.userConsent = consent(withDefaults);