diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 19928de3..cfbf8a7b 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -13,6 +13,12 @@ on:
 env:
   RUBY_YJIT_ENABLE: 1
 
+# Test has had this since it was written; Lint never did, so every push to a
+# PR ran a fresh linter to completion alongside the superseded ones.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   lint:
     name: Ruby & YAML
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f4e4e0ac..9c01c8dd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -108,7 +108,10 @@ jobs:
       contains(github.event.pull_request.labels.*.name, 'full-ci')
     needs: [ functional-test ]
     runs-on: ubuntu-latest
-    timeout-minutes: ${{ contains(matrix.ruby-version, 'jruby') && 25 || 8 }}
+    # Must fit `max_attempts * timeout_minutes` below, plus ~1 min of setup,
+    # or the last attempt gets killed mid-run and the cell reports `cancelled`
+    # -- a dead gate. JRuby: 1 + 15 + 15 = 31. MRI: 1 + 3 + 3 = 7, under 8.
+    timeout-minutes: ${{ contains(matrix.ruby-version, 'jruby') && 31 || 8 }}
     continue-on-error: ${{ matrix.experimental }}
     strategy:
       matrix:
@@ -151,17 +154,23 @@ jobs:
           ruby-cache-version: ${{ matrix.ruby-version }}-${{ matrix.gemfile }}-1
           cache-apt-packages: true
 
-      - name: Run tests (with 2 retries)
+      - name: Run tests (with 1 retry)
         uses: nick-fields/retry@v4
         with:
-          # 7 minutes stopped being enough for JRuby once the suite grew past
-          # ~600 tests: every JRuby cell on master now burns all three attempts
-          # on `Timeout of 420000ms hit` and dies at the job cap, so the cell
-          # has stopped gating anything. Locally the full suite is 390s on
-          # JRuby with vips and 434s with chunky_png -- the budget is the
-          # problem, not the driver.
+          # Measured on master run 32643567648: a clean JRuby attempt is
+          # 545-713s depending on the gemfile, so 15 min is ~26% headroom over
+          # the slowest. MRI is 128s against 3 min.
           timeout_minutes: ${{ contains(matrix.ruby-version, 'jruby') && 15 || 3 }}
-          max_attempts: 3
+          # Two, not three. A third attempt never fit inside the job cap on
+          # either engine (JRuby 3x15=45 > 25; MRI 3x3=9 > 8), so it only ever
+          # got killed partway and reported the cell as `cancelled`. Keeping
+          # the retry budget inside the cap is what makes the cell a real gate.
+          #
+          # The retry exists solely for the intermittent JRuby teardown hang
+          # (#244), which strands the process for minutes *after* the suite
+          # prints `Finished in ...`. Once #244 is fixed, drop this to a single
+          # attempt and the JRuby cap to 16 -- that halves the JRuby bill.
+          max_attempts: 2
           command: bin/rake test
 
   matrix-screenshot-driver: