diff --git a/.env.local.example b/.env.local.example
index 26d2648..bc5eb35 100644
--- a/.env.local.example
+++ b/.env.local.example
@@ -48,7 +48,7 @@ MEGA_CUSTOMER_VAT_NO=4280307796
 
 # How many dn_batches rows the /api/dn-batches/tick route claims per
 # cron hit. Tune for your batch size / model latency.
-DN_TICK_BATCH_SIZE=3
+DN_TICK_BATCH_SIZE=1
 
 # Public URL of the n8n instance (used by your local Codex MCP config).
 N8N_MCP_URL=https://wfdash.n8n.apphub.co.za/mcp-server/http
diff --git a/docs/superpowers/specs/2026-09-17-delivery-note-inbox-design.md b/docs/superpowers/specs/2026-09-17-delivery-note-inbox-design.md
index da59804..8b74598 100644
--- a/docs/superpowers/specs/2026-09-17-delivery-note-inbox-design.md
+++ b/docs/superpowers/specs/2026-09-17-delivery-note-inbox-design.md
@@ -376,7 +376,7 @@ and the Coolify environment:
 | Variable | Value | Used by |
 | --- | --- | --- |
 | `MEGA_CUSTOMER_VAT_NO` | `4280307796` | `checks.ts` → `customer_identity` |
-| `DN_TICK_BATCH_SIZE` | `3` | `/api/dn-batches/tick` claim limit |
+| `DN_TICK_BATCH_SIZE` | `1` | `/api/dn-batches/tick` claim limit. One batch per tick: a tick is fully sequential, so claiming several risks the 300s ceiling on a long document and pays for re-read pages. |
 
 `MINIMAX_API_KEY`, `MINIMAX_BASE_URL` and `MINIMAX_MODEL` already exist and
 are reused by `extract.ts`.
diff --git a/src/app/api/dn-batches/tick/route.test.ts b/src/app/api/dn-batches/tick/route.test.ts
index fc2365f..3eb04be 100644
--- a/src/app/api/dn-batches/tick/route.test.ts
+++ b/src/app/api/dn-batches/tick/route.test.ts
@@ -320,7 +320,10 @@ describe("POST /api/dn-batches/tick — happy path", () => {
     expect(body.results.map((r: { id: string }) => r.id)).toEqual(["a1", "a2"]);
   });
 
-  it("defaults DN_TICK_BATCH_SIZE to 3 when env is unset", async () => {
+  // One batch per tick by default. A tick is fully sequential — one
+  // vision call per page — so claiming several risks the route's 300s
+  // ceiling on a long document, and a timeout re-reads those pages.
+  it("defaults DN_TICK_BATCH_SIZE to 1 when env is unset", async () => {
     vi.stubEnv("DN_TICK_BATCH_SIZE", "");
     dnBatchesGetFullList.mockImplementation(
       async (opts: { filter?: string } = {}) => {
@@ -338,8 +341,8 @@ describe("POST /api/dn-batches/tick — happy path", () => {
 
     const res = await POST(postWithValidAuth());
     const body = await res.json();
-    expect(body.claimed).toBe(3);
-    expect(runBatchMock).toHaveBeenCalledTimes(3);
+    expect(body.claimed).toBe(1);
+    expect(runBatchMock).toHaveBeenCalledTimes(1);
   });
 
   it("does nothing when there are no inbox candidates", async () => {
diff --git a/src/app/api/dn-batches/tick/route.ts b/src/app/api/dn-batches/tick/route.ts
index 6865784..a9a23e3 100644
--- a/src/app/api/dn-batches/tick/route.ts
+++ b/src/app/api/dn-batches/tick/route.ts
@@ -28,7 +28,19 @@ export async function POST(request: Request) {
   }
 
   const pb = await pbAdmin();
-  const limit = Number(process.env.DN_TICK_BATCH_SIZE || 3);
+  // One batch per tick by default.
+  //
+  // Everything inside a tick is sequential — one vision call per page,
+  // then each note's checks and promotion in turn — so a tick's runtime
+  // scales with the pages it claims. Three batches of a 13-page scan can
+  // approach the 300s ceiling above, and a tick that times out mid-way
+  // leaves its batch to be reclaimed and re-read, paying for those pages
+  // twice.
+  //
+  // One batch per tick also makes n8n's execution log directly readable:
+  // one run, one document, one outcome. Raise DN_TICK_BATCH_SIZE once
+  // the page-count distribution is known and the ceiling is not a risk.
+  const limit = Number(process.env.DN_TICK_BATCH_SIZE || 1);
   const results: Record<string, unknown>[] = [];
 
   await reclaimStale(pb);