diff --git a/server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java b/server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java
index 46207b94c3af4..51ee8b045bfee 100644
--- a/server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java
+++ b/server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java
@@ -345,8 +345,13 @@ private void executeSearch(SearchTask task, SearchTimeProvider timeProvider, Sea
              * We try to set a default of max concurrent shard requests based on the node count but upper-bound it by 256 by default to keep
              * it sane. A single search request that fans out to lots of shards should not hit a cluster too hard while 256 is already a
              * lot.
+             * Yet we are still trying to guarantee some concurrency ie. if you have an index size of N shards and you are searching a
+             * single index on a single node we still search it concurrently.
              */
-            searchRequest.setMaxConcurrentShardRequests(Math.min(256, nodeCount));
+            final int numShards = shardIterators.size();
+            final int numIndices = remoteClusterIndices.size() + concreteIndices.length;
+            assert numShards >= numIndices : "found schroedingers index numShards: " + numShards + " vs. numIndices: " + numIndices;
+            searchRequest.setMaxConcurrentShardRequests(Math.min(256, nodeCount * (numShards / numIndices)));
         }
         boolean preFilterSearchShards = shouldPreFilterSearchShards(searchRequest, shardIterators);
         searchAsyncAction(task, searchRequest, shardIterators, timeProvider, connectionLookup, clusterState.version(),