diff --git a/modules/feed_manager.py b/modules/feed_manager.py
index 0f8ed83..31434ce 100644
--- a/modules/feed_manager.py
+++ b/modules/feed_manager.py
@@ -66,6 +66,9 @@ class FeedManager:
         # Semaphore to limit concurrent requests
         self._request_semaphore = asyncio.Semaphore(5)
         
+        # Serialize process_message_queue (scheduler may schedule another run if result() times out)
+        self._process_queue_lock: Optional[asyncio.Lock] = None
+        
         self.logger.info("FeedManager initialized")
     
     async def initialize(self):
@@ -1214,6 +1217,13 @@ class FeedManager:
     
     async def process_message_queue(self):
         """Process queued feed messages and send them at configured intervals"""
+        if self._process_queue_lock is None:
+            self._process_queue_lock = asyncio.Lock()
+        async with self._process_queue_lock:
+            await self._process_message_queue_inner()
+
+    async def _process_message_queue_inner(self):
+        """Body of process_message_queue (runs under _process_queue_lock)."""
         try:
             # Get all unsent messages, ordered by priority and queue time
             db_path = str(self.db_path)  # Ensure string, not Path object
diff --git a/modules/scheduler.py b/modules/scheduler.py
index 3894e11..25efff0 100644
--- a/modules/scheduler.py
+++ b/modules/scheduler.py
@@ -15,6 +15,9 @@ from typing import Dict, Tuple, Any
 from pathlib import Path
 from .utils import decode_escape_sequences, format_keyword_response_with_placeholders, get_config_timezone
 
+# process_message_queue may await long per-feed intervals across many queued items; 30s is too short.
+_FEED_MESSAGE_QUEUE_FUTURE_TIMEOUT = 600
+
 
 class MessageScheduler:
     """Manages scheduled messages and timing"""
@@ -420,7 +423,13 @@ class MessageScheduler:
                             self.bot.main_event_loop
                         )
                         try:
-                            future.result(timeout=30)  # 30 second timeout
+                            future.result(timeout=_FEED_MESSAGE_QUEUE_FUTURE_TIMEOUT)
+                        except TimeoutError:
+                            self.logger.warning(
+                                "Timed out waiting for feed message queue after %ss; "
+                                "work may still be running on the main loop (per-feed send spacing).",
+                                _FEED_MESSAGE_QUEUE_FUTURE_TIMEOUT,
+                            )
                         except Exception as e:
                             self.logger.exception(f"Error processing message queue: {e}")
                     else: