diff --git a/tests/conftest.py b/tests/conftest.py
index 873d2c3f0a..369ccebebd 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -229,12 +229,8 @@ def DummyStellarator(tmpdir_factory):
 
 
 @pytest.fixture(scope="session")
-def DummyCoilSet(tmpdir_factory):
+def DummyCoilSet():
     """Create and save a dummy coil set for testing."""
-    output_dir = tmpdir_factory.mktemp("result")
-    output_path_sym = output_dir.join("DummyCoilSet_sym.h5")
-    output_path_asym = output_dir.join("DummyCoilSet_asym.h5")
-
     eq = get("precise_QH")
     minor_radius = eq.compute("a")["a"]
 
@@ -256,25 +252,16 @@ def DummyCoilSet(tmpdir_factory):
         )
         coils.append(coil)
     coilset_sym = CoilSet(coils, NFP=eq.NFP, sym=eq.sym)
-    coilset_sym.save(output_path_sym)
 
     # equivalent CoilSet without symmetry
     coilset_asym = CoilSet.from_symmetry(coilset_sym, NFP=eq.NFP, sym=eq.sym)
-    coilset_asym.save(output_path_asym)
 
-    DummyCoilSet_out = {
-        "output_path_sym": output_path_sym,
-        "output_path_asym": output_path_asym,
-    }
-    return DummyCoilSet_out
+    return coilset_sym, coilset_asym
 
 
 @pytest.fixture(scope="session")
-def DummyMixedCoilSet(tmpdir_factory):
+def DummyMixedCoilSet():
     """Create and save a dummy mixed coil set for testing."""
-    output_dir = tmpdir_factory.mktemp("result")
-    output_path = output_dir.join("DummyMixedCoilSet.h5")
-
     tf_coil = FourierPlanarCoil(current=3, center=[2, 0, 0], normal=[0, 1, 0], r_n=[1])
     tf_coil.rotate(angle=np.pi / 4)
     tf_coilset = CoilSet(tf_coil, NFP=2, sym=True)
@@ -295,10 +282,16 @@ def DummyMixedCoilSet(tmpdir_factory):
     full_coilset = MixedCoilSet(
         (tf_coilset, vf_coilset, xyz_coil, spline_coil), check_intersection=False
     )
+    return full_coilset
+
 
-    full_coilset.save(output_path)
-    DummyMixedCoilSet_out = {"output_path": output_path}
-    return DummyMixedCoilSet_out
+@pytest.fixture(scope="session")
+def DummyNestedCoilSet(DummyCoilSet, DummyMixedCoilSet):
+    """Create and save a dummy nested coil set for testing."""
+    sym_coils, __ = DummyCoilSet
+    mixed_coils = DummyMixedCoilSet
+    nested_coils = MixedCoilSet(sym_coils, mixed_coils, check_intersection=False)
+    return nested_coils
 
 
 @pytest.fixture(scope="session")
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 6bae9dd16b..a31a9408d5 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -1314,16 +1314,25 @@ def test_second_stage_optimization_CoilSet():
 
 @pytest.mark.slow
 @pytest.mark.unit
-def test_optimize_with_all_coil_types(DummyCoilSet, DummyMixedCoilSet):
+@pytest.mark.parametrize(
+    "coil,optimizer,index",
+    [
+        (FourierPlanarCoil(), "fmintr", None),
+        (FourierRZCoil(), "fmintr", None),
+        (FourierXYZCoil(), "fmintr", None),
+        ("DummyMixedCoilSet", "fmintr", -1),  # spline coil
+        ("DummyCoilSet", "lsq-exact", 0),  # sym coils
+        ("DummyCoilSet", "lsq-exact", 1),  # asym coils
+        ("DummyMixedCoilSet", "lsq-exact", None),
+        ("DummyNestedCoilSet", "lsq-exact", None),
+    ],
+)
+def test_optimize_with_all_coil_types(coil, optimizer, index, request):
     """Test optimizing for every type of coil and dummy coil sets."""
-    sym_coils = load(load_from=str(DummyCoilSet["output_path_sym"]), file_format="hdf5")
-    asym_coils = load(
-        load_from=str(DummyCoilSet["output_path_asym"]), file_format="hdf5"
-    )
-    mixed_coils = load(
-        load_from=str(DummyMixedCoilSet["output_path"]), file_format="hdf5"
-    )
-    nested_coils = MixedCoilSet(sym_coils, mixed_coils, check_intersection=False)
+    if isinstance(coil, str):
+        coil = request.getfixturevalue(coil)
+        coil = coil[index] if index is not None else coil
+
     eq = Equilibrium()
     # not attempting to accurately calc B for this test,
     # so make the grids very coarse
@@ -1349,9 +1358,7 @@ def test(c, method):
         (c,), _ = optimizer.optimize(c, obj, maxiter=2, ftol=0, xtol=1e-15)
 
         # now check with optimizing geometry and actually check result
-        objs = [
-            CoilLength(c, target=target),
-        ]
+        objs = [CoilLength(c, target=target)]
         extra_msg = ""
         if isinstance(c, MixedCoilSet):
             # just to check they work without error
@@ -1366,7 +1373,7 @@ def test(c, method):
 
         obj = ObjectiveFunction(objs)
 
-        (c,), _ = optimizer.optimize(c, obj, maxiter=25, ftol=5e-3, xtol=1e-15)
+        (c,), _ = optimizer.optimize(c, obj, maxiter=50, ftol=5e-3, xtol=1e-15)
         flattened_coils = tree_leaves(
             c, is_leaf=lambda x: isinstance(x, _Coil) and not isinstance(x, CoilSet)
         )
@@ -1375,21 +1382,7 @@ def test(c, method):
             lengths, target, rtol=rtol, err_msg=f"lengths {c}" + extra_msg
         )
 
-    spline_coil = mixed_coils.coils[-1].copy()
-
-    # single coil
-    test(FourierPlanarCoil(), "fmintr")
-    test(FourierRZCoil(), "fmintr")
-    test(FourierXYZCoil(), "fmintr")
-    test(spline_coil, "fmintr")
-
-    # CoilSet
-    test(sym_coils, "lsq-exact")
-    test(asym_coils, "lsq-exact")
-
-    # MixedCoilSet
-    test(mixed_coils, "lsq-exact")
-    test(nested_coils, "lsq-exact")
+    test(coil, optimizer)
 
 
 @pytest.mark.unit