diff --git a/tests/unit/logic/cut_filament/test_cut_filament.cpp b/tests/unit/logic/cut_filament/test_cut_filament.cpp
index d2275d4..a54d6bf 100644
--- a/tests/unit/logic/cut_filament/test_cut_filament.cpp
+++ b/tests/unit/logic/cut_filament/test_cut_filament.cpp
@@ -21,12 +21,11 @@ using Catch::Matchers::Equals;
 
 #include "../helpers/helpers.ipp"
 
-void CutSlot(uint8_t cutSlot) {
+void CutSlot(logic::CutFilament &cf, uint8_t cutSlot) {
 
     ForceReinitAllAutomata();
 
-    logic::CutFilament cf;
-    REQUIRE(VerifyState(cf, false, mi::Idler::IdleSlotIndex(), 0, false, ml::off, ml::off, ErrorCode::OK, ProgressCode::OK));
+    REQUIRE(VerifyEnvironmentState(false, mi::Idler::IdleSlotIndex(), 0, false, ml::off, ml::off));
 
     EnsureActiveSlotIndex(cutSlot);
 
@@ -87,12 +86,30 @@ void CutSlot(uint8_t cutSlot) {
 
 TEST_CASE("cut_filament::cut0", "[cut_filament]") {
     for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
-        CutSlot(cutSlot);
+        logic::CutFilament cf;
+        CutSlot(cf, cutSlot);
     }
 }
 
 TEST_CASE("cut_filament::invalid_slot", "[cut_filament]") {
-    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
-        InvalidSlot<logic::CutFilament>(config::toolCount, cutSlot);
+    for (uint8_t activeSlot = 0; activeSlot < config::toolCount; ++activeSlot) {
+        logic::CutFilament cf;
+        InvalidSlot<logic::CutFilament>(cf, activeSlot, config::toolCount);
+    }
+}
+
+TEST_CASE("cut_filament::state_machine_reusal", "[cut_filament]") {
+    logic::CutFilament cf;
+    for (uint8_t activeSlot = 0; activeSlot < config::toolCount; ++activeSlot) {
+        InvalidSlot<logic::CutFilament>(cf, activeSlot, config::toolCount);
+    }
+
+    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
+        CutSlot(cf, cutSlot);
+    }
+
+    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
+        CutSlot(cf, cutSlot);
+        InvalidSlot<logic::CutFilament>(cf, cutSlot, config::toolCount);
     }
 }
diff --git a/tests/unit/logic/eject_filament/test_eject_filament.cpp b/tests/unit/logic/eject_filament/test_eject_filament.cpp
index d9671a5..85aa602 100644
--- a/tests/unit/logic/eject_filament/test_eject_filament.cpp
+++ b/tests/unit/logic/eject_filament/test_eject_filament.cpp
@@ -70,12 +70,8 @@ TEST_CASE("eject_filament::eject0", "[eject_filament][.]") {
 }
 
 TEST_CASE("eject_filament::invalid_slot", "[eject_filament]") {
-    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
-        InvalidSlot<logic::EjectFilament>(config::toolCount, cutSlot);
+    for (uint8_t activeSlot = 0; activeSlot < config::toolCount; ++activeSlot) {
+        logic::EjectFilament ef;
+        InvalidSlot<logic::EjectFilament>(ef, activeSlot, config::toolCount);
     }
 }
-
-// comments:
-// The tricky part of the whole state machine are the edge cases - filament not loaded, stall guards etc.
-// ... all the external influence we can get on the real HW
-// But the good news is we can simulate them all in the unit test and thus ensure proper handling
diff --git a/tests/unit/logic/helpers/helpers.ipp b/tests/unit/logic/helpers/helpers.ipp
index 982a65c..1e538ec 100644
--- a/tests/unit/logic/helpers/helpers.ipp
+++ b/tests/unit/logic/helpers/helpers.ipp
@@ -1,7 +1,5 @@
-// LED checked at selector's index
-template<typename SM>
-bool VerifyState(SM &uf, bool filamentLoaded, uint8_t idlerSlotIndex, uint8_t selectorSlotIndex,
-    bool findaPressed, ml::Mode greenLEDMode, ml::Mode redLEDMode, ErrorCode err, ProgressCode topLevelProgress) {
+bool VerifyEnvironmentState(bool filamentLoaded, uint8_t idlerSlotIndex, uint8_t selectorSlotIndex,
+    bool findaPressed, ml::Mode greenLEDMode, ml::Mode redLEDMode) {
     CHECKED_ELSE(mg::globals.FilamentLoaded() == filamentLoaded) { return false; }
     CHECKED_ELSE(mm::axes[mm::Idler].pos == mi::Idler::SlotPosition(idlerSlotIndex).v) { return false; }
     CHECKED_ELSE(mi::idler.Engaged() == (idlerSlotIndex < config::toolCount)) { return false; }
@@ -19,8 +17,19 @@ bool VerifyState(SM &uf, bool filamentLoaded, uint8_t idlerSlotIndex, uint8_t se
             CHECKED_ELSE(ml::leds.Mode(selectorSlotIndex, ml::green) == greenLEDMode) { return false; }
         }
     }
+    return true;
+}
 
-    CHECKED_ELSE(uf.Error() == err) { return false; }
+// LED checked at selector's index
+template<typename SM>
+bool VerifyState(SM &uf, bool filamentLoaded, uint8_t idlerSlotIndex, uint8_t selectorSlotIndex,
+    bool findaPressed, ml::Mode greenLEDMode, ml::Mode redLEDMode, ErrorCode err, ProgressCode topLevelProgress) {
+
+    VerifyEnvironmentState(filamentLoaded, idlerSlotIndex, selectorSlotIndex, findaPressed, greenLEDMode, redLEDMode);
+
+    CHECKED_ELSE(uf.Error() == err) {
+        return false;
+    }
     CHECKED_ELSE(uf.TopLevelState() == topLevelProgress) { return false; }
     return true;
 }
@@ -52,12 +61,13 @@ bool VerifyState2(SM &uf, bool filamentLoaded, uint8_t idlerSlotIndex, uint8_t s
     return true;
 }
 
+
+
 template<typename SM>
-void InvalidSlot(uint8_t invSlot, uint8_t activeSlot){
+void InvalidSlot(SM &logicSM,  uint8_t activeSlot, uint8_t invSlot){
     ForceReinitAllAutomata();
 
-    SM logicSM;
-    REQUIRE(VerifyState(logicSM, false, mi::Idler::IdleSlotIndex(), 0, false, ml::off, ml::off, ErrorCode::OK, ProgressCode::OK));
+    REQUIRE(VerifyEnvironmentState(false, mi::Idler::IdleSlotIndex(), 0, false, ml::off, ml::off));
 
     EnsureActiveSlotIndex(activeSlot);
 
diff --git a/tests/unit/logic/load_filament/test_load_filament.cpp b/tests/unit/logic/load_filament/test_load_filament.cpp
index 10de810..84d4a66 100644
--- a/tests/unit/logic/load_filament/test_load_filament.cpp
+++ b/tests/unit/logic/load_filament/test_load_filament.cpp
@@ -161,7 +161,24 @@ TEST_CASE("load_filament::failed_load_to_finda_0-4_resolve_help_second_fail", "[
 }
 
 TEST_CASE("load_filament::invalid_slot", "[load_filament]") {
-    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
-        InvalidSlot<logic::LoadFilament>(config::toolCount, cutSlot);
+    for (uint8_t activeSlot = 0; activeSlot < config::toolCount; ++activeSlot) {
+        logic::LoadFilament lf;
+        InvalidSlot<logic::LoadFilament>(lf, activeSlot, config::toolCount);
+    }
+}
+
+TEST_CASE("load_filament::state_machine_reusal", "[load_filament]") {
+    logic::LoadFilament lf;
+
+    for (uint8_t fromSlot = 0; fromSlot < config::toolCount; ++fromSlot) {
+        for (uint8_t toSlot = 0; toSlot < config::toolCount + 2; ++toSlot) {
+            logic::LoadFilament lf;
+            if (toSlot >= config::toolCount) {
+                InvalidSlot<logic::LoadFilament>(lf, fromSlot, toSlot);
+            } else {
+                LoadFilamentCommonSetup(toSlot, lf);
+                LoadFilamentSuccessful(toSlot, lf);
+            }
+        }
     }
 }
diff --git a/tests/unit/logic/tool_change/test_tool_change.cpp b/tests/unit/logic/tool_change/test_tool_change.cpp
index 3f252c9..6772660 100644
--- a/tests/unit/logic/tool_change/test_tool_change.cpp
+++ b/tests/unit/logic/tool_change/test_tool_change.cpp
@@ -21,11 +21,9 @@ using Catch::Matchers::Equals;
 
 #include "../helpers/helpers.ipp"
 
-void ToolChange(uint8_t fromSlot, uint8_t toSlot) {
+void ToolChange(logic::ToolChange tc, uint8_t fromSlot, uint8_t toSlot) {
     ForceReinitAllAutomata();
 
-    logic::ToolChange tc;
-
     EnsureActiveSlotIndex(fromSlot);
 
     // restart the automaton
@@ -55,11 +53,9 @@ void ToolChange(uint8_t fromSlot, uint8_t toSlot) {
     REQUIRE(mg::globals.ActiveSlot() == toSlot);
 }
 
-void NoToolChange(uint8_t fromSlot, uint8_t toSlot) {
+void NoToolChange(logic::ToolChange tc, uint8_t fromSlot, uint8_t toSlot) {
     ForceReinitAllAutomata();
 
-    logic::ToolChange tc;
-
     EnsureActiveSlotIndex(fromSlot);
 
     // restart the automaton
@@ -73,17 +69,35 @@ void NoToolChange(uint8_t fromSlot, uint8_t toSlot) {
 TEST_CASE("tool_change::test0", "[tool_change]") {
     for (uint8_t fromSlot = 0; fromSlot < config::toolCount; ++fromSlot) {
         for (uint8_t toSlot = 0; toSlot < config::toolCount; ++toSlot) {
+            logic::ToolChange tc;
             if (fromSlot != toSlot) {
-                ToolChange(fromSlot, toSlot);
+                ToolChange(tc, fromSlot, toSlot);
             } else {
-                NoToolChange(fromSlot, toSlot);
+                NoToolChange(tc, fromSlot, toSlot);
             }
         }
     }
 }
 
 TEST_CASE("tool_change::invalid_slot", "[tool_change]") {
-    for (uint8_t cutSlot = 0; cutSlot < config::toolCount; ++cutSlot) {
-        InvalidSlot<logic::ToolChange>(config::toolCount, cutSlot);
+    for (uint8_t fromSlot = 0; fromSlot < config::toolCount; ++fromSlot) {
+        logic::ToolChange tc;
+        InvalidSlot<logic::ToolChange>(tc, fromSlot, config::toolCount);
+    }
+}
+
+TEST_CASE("tool_change::state_machine_reusal", "[tool_change]") {
+    logic::ToolChange tc;
+
+    for (uint8_t fromSlot = 0; fromSlot < config::toolCount; ++fromSlot) {
+        for (uint8_t toSlot = 0; toSlot < config::toolCount + 2; ++toSlot) {
+            if (toSlot >= config::toolCount) {
+                InvalidSlot<logic::ToolChange>(tc, fromSlot, toSlot);
+            } else if (fromSlot != toSlot) {
+                ToolChange(tc, fromSlot, toSlot);
+            } else {
+                NoToolChange(tc, fromSlot, toSlot);
+            }
+        }
     }
 }