diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index f3dfbf1a2..12351a2c6 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -69,9 +69,16 @@ integration)
     RETURN_CODE=$?
     ;;
 samples)
-    if [[ -f samples/pom.xml ]]
+    SAMPLES_DIR=samples
+    # only run ITs in snapshot/ on presubmit PRs. run ITs in all 3 samples/ subdirectories otherwise.
+    if [[ ! -z ${KOKORO_GITHUB_PULL_REQUEST_NUMBER} ]]
     then
-        pushd samples
+      SAMPLES_DIR=samples/snapshot
+    fi
+
+    if [[ -f ${SAMPLES_DIR}/pom.xml ]]
+    then
+        pushd {SAMPLES_DIR}
         mvn -B \
           -Penable-samples \
           -DtrimStackTrace=false \
diff --git a/synth.metadata b/synth.metadata
index ba2c15b4d..19392ddb2 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -11,7 +11,7 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "b65ef07d99946d23e900ef2cc490274a16edd336"
+        "sha": "27e0e916cbfdb3d5ff6639b686cc04f78a0b0386"
       }
     }
   ],