diff --git a/README.md b/README.md
index dc8f4fa..cfb6861 100644
--- a/README.md
+++ b/README.md
@@ -22,8 +22,9 @@ services:
       namespace: keepalive
 
   - adapter: valkey
-    # One service can override the global interval.
+    # One service can override the global interval and counter key.
     interval: 30s
+    counter_key: valkey-counter
     config:
       url: valkey://default@valkey-a.example.com:6379
 
@@ -56,8 +57,11 @@ services:
 `interval` at the root sets the default schedule for every service and defaults to `1m`.
 `interval` inside a service overrides that default only for that service.
 In the example above, every service runs every `1m` except `valkey`, which runs every `30s`.
+Interval values use Go duration syntax, for example `30s`, `5m`, `1h`, `1h30m`, or `1.5h`. Plain integers are treated as seconds, so `90` means `90s`.
 
-`counter_key` can be set globally or per service. Per-service values override global values.
+`counter_key` at the root sets the default counter key for every service and defaults to `counter`.
+`counter_key` inside a service overrides that default only for that service.
+In the example above, every service writes `counter` except `valkey`, which writes `valkey-counter`.
 
 ## Supported adapters
 
diff --git a/config.example.yml b/config.example.yml
index 3276f5a..68a449b 100644
--- a/config.example.yml
+++ b/config.example.yml
@@ -1,4 +1,5 @@
 # Optional default interval shared by every service.
+# Examples: 30s, 5m, 1h, 1h30m, 1.5h, or 90 for 90 seconds.
 interval: 1m
 counter_key: counter
 
@@ -9,8 +10,9 @@ services:
       namespace: keepalive
 
   - adapter: valkey
-    # Example: this service runs every 30s while others use the root interval.
+    # Example: this service overrides root interval and counter_key.
     interval: 30s
+    counter_key: valkey-counter
     config:
       url: valkey://default@valkey-a.example.com:6379
 
diff --git a/config.go b/config.go
index 8639a07..f2d1691 100644
--- a/config.go
+++ b/config.go
@@ -138,7 +138,7 @@ func parseConfigInterval(field, value string, def time.Duration) (time.Duration,
 		}
 		return d, nil
 	}
-	return 0, fmt.Errorf("%s must be a duration like 30s or an integer number of seconds", field)
+	return 0, fmt.Errorf("%s must be a duration like 30s, 5m, or 1h30m, or an integer number of seconds", field)
 }
 
 func valueOrDefault(value, def string) string {
diff --git a/config_test.go b/config_test.go
index 8a04d38..cfbb4b0 100644
--- a/config_test.go
+++ b/config_test.go
@@ -51,6 +51,15 @@ func TestConfigExampleYMLParses(t *testing.T) {
 	if services[2].Interval != time.Minute {
 		t.Fatalf("services[2].Interval = %s, want 1m", services[2].Interval)
 	}
+	if services[0].Config["counter_key"] != "counter" {
+		t.Fatalf("services[0] counter_key = %q, want counter", services[0].Config["counter_key"])
+	}
+	if services[1].Config["counter_key"] != "valkey-counter" {
+		t.Fatalf("services[1] counter_key = %q, want valkey-counter", services[1].Config["counter_key"])
+	}
+	if services[2].Config["counter_key"] != "counter" {
+		t.Fatalf("services[2] counter_key = %q, want counter", services[2].Config["counter_key"])
+	}
 }
 
 func TestFirstExistingConfigFileFindsYMLFallback(t *testing.T) {
@@ -156,6 +165,26 @@ func TestNormalizeConfigAppliesGlobalAndServiceDefaults(t *testing.T) {
 	}
 }
 
+func TestNormalizeConfigParsesCompoundAndFractionalIntervals(t *testing.T) {
+	services, err := normalizeConfig(appConfig{
+		Interval: "1h30m",
+		Services: []serviceFileConfig{
+			{Adapter: "redis", Config: map[string]string{"url": "redis://cache.example.com:6379"}},
+			{Adapter: "redis", Interval: "1.5h", Config: map[string]string{"url": "redis://other.example.com:6379"}},
+		},
+	})
+	if err != nil {
+		t.Fatalf("normalizeConfig returned error: %v", err)
+	}
+
+	if services[0].Interval != 90*time.Minute {
+		t.Fatalf("services[0].Interval = %s, want 1h30m", services[0].Interval)
+	}
+	if services[1].Interval != 90*time.Minute {
+		t.Fatalf("services[1].Interval = %s, want 1.5h", services[1].Interval)
+	}
+}
+
 func TestNormalizeConfigRejectsNonPositiveInterval(t *testing.T) {
 	_, err := normalizeConfig(appConfig{
 		Interval: "0s",