diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7f5da2e3c9..f5d8186490 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1196,7 +1196,7 @@ jobs:
           if-no-files-found: error
 
   # Manual editing accuracy in the built Studio, gated against the base branch's baseline.json. A pull request
-  # runs the `pr` slice in 15 shards; the merge queue runs the full grid in 20, so nothing reaches main unmeasured.
+  # runs the `pr` slice in 15 shards; the merge queue runs the full grid in 30, so nothing reaches main unmeasured.
   # The gate job below repeats both shard counts.
   studio-edit-accuracy:
     name: "Studio: edit accuracy (${{ matrix.shard }}/${{ strategy.job-total }})"
@@ -1208,7 +1208,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        shard: ${{ fromJSON(github.event_name == 'merge_group' && '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]' || '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]') }}
+        shard: ${{ fromJSON(github.event_name == 'merge_group' && '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]' || '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]') }}
     env:
       EDIT_ACCURACY_GRID: ${{ github.event_name == 'merge_group' && 'full' || 'pr' }}
     steps:
@@ -1282,7 +1282,7 @@ jobs:
         shard: ${{ fromJSON(needs.studio-edit-accuracy-retry-plan.outputs.shards) }}
     env:
       EDIT_ACCURACY_GRID: ${{ github.event_name == 'merge_group' && 'full' || 'pr' }}
-      SHARDS: ${{ github.event_name == 'merge_group' && 20 || 15 }}
+      SHARDS: ${{ github.event_name == 'merge_group' && 30 || 15 }}
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
       - uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2
@@ -1338,7 +1338,7 @@ jobs:
         id: gate
         # Smoothness and newly passing cases are reported, not gated; a case fails only if it fails 2 of its 3 runs.
         env:
-          SHARDS: ${{ github.event_name == 'merge_group' && 20 || 15 }}
+          SHARDS: ${{ github.event_name == 'merge_group' && 30 || 15 }}
         run: |
           set +e
           mapfile -t RESULTS < <(find /tmp/edit-accuracy-shards -name results.json | sort)
diff --git a/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs b/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs
index c95fb034e8..75a468f3b2 100644
--- a/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs
+++ b/packages/studio/tests/e2e/edit-accuracy/grid.test.mjs
@@ -51,7 +51,7 @@ describe("shards", () => {
   const seconds = (cases) => cases.reduce((sum, c) => sum + (timings[c.id] ?? 0), 0);
 
   it.each([
-    ["full", 20],
+    ["full", 30],
     ["pr", 15],
   ])(
     "put each %s case in one of %i shards, all within one case's time of each other",
@@ -72,7 +72,7 @@ describe("shards", () => {
 
   // Each shard starts with its slowest cases; 1.68x is the slowest runner seen across 100 merge-queue shards.
   it.each([
-    ["full", 20],
+    ["full", 30],
     ["pr", 15],
   ])(
     "let every %s shard of %i start its slowest cases on a 1.68x runner without a slow stop",