diff --git a/simulation/codex_lm.py b/simulation/codex_lm.py
index 209578032..1ac8caaad 100644
--- a/simulation/codex_lm.py
+++ b/simulation/codex_lm.py
@@ -70,17 +70,21 @@ below asks for, with no preamble and no commentary.
 class CodexLM:
     """Callable implementing GEPA's LanguageModel protocol via codex exec."""
 
-    def __init__(self, model: str = "gpt-5.6-sol", timeout: int = 600,
-                 require_marker: str = None, effort: str = "xhigh"):
+    def __init__(self, model: str = "gpt-5.6-sol", timeout: int = 900,
+                 require_marker: str = None, effort: str = "high"):
         self.model = model
         self.timeout = timeout
 
         # Reasoning effort for the searcher. Passed as a per-call config
         # override so it always wins over whatever the harness home's
         # config.toml was written with (that file is only created on
-        # first use and never rewritten). Search/reflection agents run
-        # at xhigh by default; drop to high only if wall-clock per
-        # proposal becomes the bottleneck.
+        # first use and never rewritten). The default is high: exp-018's
+        # gepa arm ran at xhigh and lost 4 of 13 iterations to the 600s
+        # reflection timeout while taking nine hours for 150 evals — the
+        # evolutionary loop supplies the search, so iteration throughput
+        # beats per-proposal depth. Request xhigh explicitly
+        # (codex:<model>:xhigh) when a deep single proposal is the
+        # point.
         self.effort = effort
 
         # require_marker is a substring every valid completion must contain
diff --git a/simulation/run_gepa_code.py b/simulation/run_gepa_code.py
index 071da8670..cb3678b19 100644
--- a/simulation/run_gepa_code.py
+++ b/simulation/run_gepa_code.py
@@ -139,7 +139,7 @@ def main() -> None:
                         help="rotate gepa <-> meta_harness on plateaus")
     parser.add_argument("--no-adaptive", dest="adaptive",
                         action="store_false")
-    parser.add_argument("--reflection-timeout", type=int, default=600,
+    parser.add_argument("--reflection-timeout", type=int, default=900,
                         help="seconds to allow one reflection call. Raise "
                         "it for large seeds, whose reflections are slow.")
     parser.add_argument("--seed-file", default=None,
@@ -168,17 +168,17 @@ def main() -> None:
     reflection_lm = args.reflection_lm
     if reflection_lm.startswith("codex:"):
         # codex:<model>[:<effort>] — e.g. codex:gpt-5.6-sol:xhigh.
-        # Searcher agents default to xhigh reasoning effort; a large
-        # seed makes reflection slow (a thousand-line candidate takes
-        # codex well past the ten minute default, and a timeout there
-        # costs a whole iteration to a stub proposal), so the timeout
-        # knob matters more at higher effort.
+        # Searchers default to high effort with a 900s timeout after
+        # exp-018 measured xhigh at 600s losing roughly a third of its
+        # iterations to reflection timeouts; a large seed makes
+        # reflection slow, so the timeout knob matters more at higher
+        # effort.
         spec = reflection_lm.split(":")
         reflection_lm = CodexLM(
             model=spec[1],
             require_marker="package main",
             timeout=args.reflection_timeout,
-            effort=spec[2] if len(spec) > 2 else "xhigh",
+            effort=spec[2] if len(spec) > 2 else "high",
         )
     elif reflection_lm.startswith("claude:"):
         # claude:<model>[:<effort>] — e.g. claude:claude-opus-5:medium.