diff --git a/Marlin/src/gcode/parser.cpp b/Marlin/src/gcode/parser.cpp
index 99738461de..b692c818aa 100644
--- a/Marlin/src/gcode/parser.cpp
+++ b/Marlin/src/gcode/parser.cpp
@@ -188,7 +188,7 @@ void GCodeParser::parse(char *p) {
 
       // Bail if there's no command code number
       if (!TERN(SIGNED_CODENUM, NUMERIC_SIGNED(*p), NUMERIC(*p))) {
-        if (TERN0(HAS_MULTI_EXTRUDER, letter == 'T')) {
+        if (E_TERN0(letter == 'T')) {
           p[0] = '*'; p[1] = '\0'; string_arg = p; // Convert 'T' alone into 'T*'
           command_letter = letter;
         }
diff --git a/Marlin/src/gcode/temp/M306.cpp b/Marlin/src/gcode/temp/M306.cpp
index b3f5b6b97b..7e79581f2b 100644
--- a/Marlin/src/gcode/temp/M306.cpp
+++ b/Marlin/src/gcode/temp/M306.cpp
@@ -49,7 +49,7 @@
  */
 
 void GcodeSuite::M306() {
-  const uint8_t e = TERN0(HAS_MULTI_EXTRUDER, parser.intval('E', active_extruder));
+  const uint8_t e = E_TERN0(parser.intval('E', active_extruder));
   if (e >= (EXTRUDERS)) {
     SERIAL_ECHOLNPGM("?(E)xtruder index out of range (0-", (EXTRUDERS) - 1, ").");
     return;
diff --git a/Marlin/src/lcd/extui/dgus/mks/DGUSScreenHandler.cpp b/Marlin/src/lcd/extui/dgus/mks/DGUSScreenHandler.cpp
index d39c3079be..bd774f7523 100644
--- a/Marlin/src/lcd/extui/dgus/mks/DGUSScreenHandler.cpp
+++ b/Marlin/src/lcd/extui/dgus/mks/DGUSScreenHandler.cpp
@@ -1088,7 +1088,7 @@ void DGUSScreenHandlerMKS::filamentUnload(DGUS_VP_Variable &var, void *val_ptr)
 
     if (filament_data.action == 0) { // Go back to utility screen
       TERN_(HAS_EXTRUDERS, thermalManager.setTargetHotend(e_temp, 0));
-      TERN_(HAS_MULTI_EXTRUDER, thermalManager.setTargetHotend(e_temp, 1));
+      E_TERN_(thermalManager.setTargetHotend(e_temp, 1));
       gotoScreen(DGUS_SCREEN_UTILITY);
       return;
     }
diff --git a/Marlin/src/lcd/extui/mks_ui/draw_change_speed.cpp b/Marlin/src/lcd/extui/mks_ui/draw_change_speed.cpp
index 556c855b25..826d6e1a9d 100644
--- a/Marlin/src/lcd/extui/mks_ui/draw_change_speed.cpp
+++ b/Marlin/src/lcd/extui/mks_ui/draw_change_speed.cpp
@@ -56,7 +56,7 @@ static void event_handler(lv_obj_t *obj, lv_event_t event) {
       else {
         const int16_t new_flow = _MIN(MAX_EXT_SPEED_PERCENT, planner.flow_percentage[0] + uiCfg.stepPrintSpeed);
         planner.set_flow(0, new_flow);
-        TERN_(HAS_MULTI_EXTRUDER, planner.set_flow(1, new_flow));
+        E_TERN_(planner.set_flow(1, new_flow));
       }
       disp_print_speed();
       break;
@@ -66,7 +66,7 @@ static void event_handler(lv_obj_t *obj, lv_event_t event) {
       else {
         const int16_t new_flow = _MAX(MIN_EXT_SPEED_PERCENT, planner.flow_percentage[0] - uiCfg.stepPrintSpeed);
         planner.set_flow(0, new_flow);
-        TERN_(HAS_MULTI_EXTRUDER, planner.set_flow(1, new_flow));
+        E_TERN_(planner.set_flow(1, new_flow));
       }
       disp_print_speed();
       break;
diff --git a/Marlin/src/lcd/extui/mks_ui/draw_dialog.cpp b/Marlin/src/lcd/extui/mks_ui/draw_dialog.cpp
index 5be5e96e13..596c78c6aa 100644
--- a/Marlin/src/lcd/extui/mks_ui/draw_dialog.cpp
+++ b/Marlin/src/lcd/extui/mks_ui/draw_dialog.cpp
@@ -103,7 +103,7 @@ static void btn_ok_event_cb(lv_obj_t *btn, lv_event_t event) {
         if (card.isFileOpen()) {
           feedrate_percentage = 100;
           TERN_(HAS_EXTRUDERS, planner.set_flow(0, 100));
-          TERN_(HAS_MULTI_EXTRUDER, planner.set_flow(1, 100));
+          E_TERN_(planner.set_flow(1, 100));
           card.startOrResumeFilePrinting();
           TERN_(POWER_LOSS_RECOVERY, recovery.prepare());
           once_flag = false;
diff --git a/Marlin/src/lcd/extui/mks_ui/draw_preHeat.cpp b/Marlin/src/lcd/extui/mks_ui/draw_preHeat.cpp
index a024f050be..eea354f732 100644
--- a/Marlin/src/lcd/extui/mks_ui/draw_preHeat.cpp
+++ b/Marlin/src/lcd/extui/mks_ui/draw_preHeat.cpp
@@ -235,7 +235,7 @@ void disp_ext_heart() {
 
 void disp_temp_type() {
   if (uiCfg.curTempType == 0) {
-    if (TERN0(HAS_MULTI_EXTRUDER, uiCfg.extruderIndex == 1)) {
+    if (E_TERN0(uiCfg.extruderIndex == 1)) {
       lv_imgbtn_set_src_both(buttonType, "F:/bmp_extru2.bin");
       if (gCfgItems.multiple_language) {
         lv_label_set_text(labelType, preheat_menu.ext2);
diff --git a/Marlin/src/lcd/extui/mks_ui/draw_ui.cpp b/Marlin/src/lcd/extui/mks_ui/draw_ui.cpp
index 45ec98cefd..b3ae273a48 100644
--- a/Marlin/src/lcd/extui/mks_ui/draw_ui.cpp
+++ b/Marlin/src/lcd/extui/mks_ui/draw_ui.cpp
@@ -651,7 +651,7 @@ char *creat_title_text() {
         if (card.isFileOpen()) {
           feedrate_percentage = 100;
           TERN_(HAS_EXTRUDERS, planner.set_flow(0, 100));
-          TERN_(HAS_MULTI_EXTRUDER, planner.set_flow(1, 100));
+          E_TERN_(planner.set_flow(1, 100));
           card.startOrResumeFilePrinting();
           TERN_(POWER_LOSS_RECOVERY, recovery.prepare());
           once_flag = false;
diff --git a/Marlin/src/lcd/extui/mks_ui/wifi_module.cpp b/Marlin/src/lcd/extui/mks_ui/wifi_module.cpp
index 8a83ff62c0..8ba81a6f2e 100644
--- a/Marlin/src/lcd/extui/mks_ui/wifi_module.cpp
+++ b/Marlin/src/lcd/extui/mks_ui/wifi_module.cpp
@@ -1072,7 +1072,7 @@ static void wifi_gcode_exec(uint8_t * const cmd_line) {
                   //saved_feedrate_percentage = feedrate_percentage;
                   feedrate_percentage = 100;
                   TERN_(HAS_EXTRUDERS, planner.set_flow(0, 100));
-                  TERN_(HAS_MULTI_EXTRUDER, planner.set_flow(1, 100));
+                  E_TERN_(planner.set_flow(1, 100));
                   card.startOrResumeFilePrinting();
                   TERN_(POWER_LOSS_RECOVERY, recovery.prepare());
                   once_flag = false;
diff --git a/Marlin/src/module/ft_motion.cpp b/Marlin/src/module/ft_motion.cpp
index af6b24b5c4..f6113c398e 100644
--- a/Marlin/src/module/ft_motion.cpp
+++ b/Marlin/src/module/ft_motion.cpp
@@ -390,8 +390,10 @@ bool FTMotion::plan_next_block() {
     #endif
 
     // Cache the extruder index / axis for this block
+    #if ANY(HAS_MULTI_EXTRUDER, MIXING_EXTRUDER)
+      stepper.stepper_extruder = current_block->extruder;
+    #endif
     #if ENABLED(DISTINCT_E_FACTORS)
-      stepper_extruder = current_block->extruder;
       block_extruder_axis = E_AXIS_N(current_block->extruder);
     #endif
 
diff --git a/Marlin/src/module/stepper.cpp b/Marlin/src/module/stepper.cpp
index 3584e1290e..2a10c83800 100644
--- a/Marlin/src/module/stepper.cpp
+++ b/Marlin/src/module/stepper.cpp
@@ -1593,7 +1593,7 @@ void Stepper::isr() {
   // FT Motion can be toggled if Standard Motion is also active
   const bool using_ftMotion = ENABLED(NO_STANDARD_MOTION) || TERN0(FT_MOTION, ftMotion.cfg.active);
 
-  // Storage for the timer value of the next possible ISR, used in this do loop
+  // Storage for the soonest timer value of the next possible ISR, used in this do loop
   hal_timer_t min_ticks;
 
   // Loop until all events for this ISR have been issued