Use E_AXIS_N where it makes sense

Marlin/src/lcd/menu/menu_advanced.cpp

@@ -368,7 +368,7 @@ void menu_advanced_temperature() {
       if (e == active_extruder)
         _planner_refresh_positioning();
       else
-        planner.steps_to_mm[E_AXIS + e] = 1.0f / planner.settings.axis_steps_per_mm[E_AXIS + e];
+        planner.steps_to_mm[E_AXIS_N(e)] = 1.0f / planner.settings.axis_steps_per_mm[E_AXIS_N(e)];
     }
     void _planner_refresh_e0_positioning() { _planner_refresh_e_positioning(0); }
     void _planner_refresh_e1_positioning() { _planner_refresh_e_positioning(1); }

Marlin/src/module/configuration_store.cpp

@@ -2353,7 +2353,7 @@ void MarlinSettings::reset(PORTARG_SOLO) {
       CONFIG_ECHO_START();
       for (uint8_t i = 0; i < E_STEPPERS; i++) {
         SERIAL_ECHOPAIR_P(port, "  M203 T", (int)i);
-        SERIAL_ECHOLNPAIR_P(port, " E", VOLUMETRIC_UNIT(planner.settings.max_feedrate_mm_s[E_AXIS + i]));
+        SERIAL_ECHOLNPAIR_P(port, " E", VOLUMETRIC_UNIT(planner.settings.max_feedrate_mm_s[E_AXIS_N(i)]));
       }
     #endif
 
@@ -2370,7 +2370,7 @@ void MarlinSettings::reset(PORTARG_SOLO) {
       CONFIG_ECHO_START();
       for (uint8_t i = 0; i < E_STEPPERS; i++) {
         SERIAL_ECHOPAIR_P(port, "  M201 T", (int)i);
-        SERIAL_ECHOLNPAIR_P(port, " E", VOLUMETRIC_UNIT(planner.settings.max_acceleration_mm_per_s2[E_AXIS + i]));
+        SERIAL_ECHOLNPAIR_P(port, " E", VOLUMETRIC_UNIT(planner.settings.max_acceleration_mm_per_s2[E_AXIS_N(i)]));
       }
     #endif
 

Marlin/src/module/planner.cpp

@@ -2646,8 +2646,8 @@ bool Planner::buffer_segment(const float &a, const float &b, const float &c, con
 
   // When changing extruders recalculate steps corresponding to the E position
   #if ENABLED(DISTINCT_E_FACTORS)
-    if (last_extruder != extruder && settings.axis_steps_per_mm[E_AXIS_N(extruder)] != settings.axis_steps_per_mm[E_AXIS + last_extruder]) {
-      position[E_AXIS] = LROUND(position[E_AXIS] * settings.axis_steps_per_mm[E_AXIS_N(extruder)] * steps_to_mm[E_AXIS + last_extruder]);
+    if (last_extruder != extruder && settings.axis_steps_per_mm[E_AXIS_N(extruder)] != settings.axis_steps_per_mm[E_AXIS_N(last_extruder)]) {
+      position[E_AXIS] = LROUND(position[E_AXIS] * settings.axis_steps_per_mm[E_AXIS_N(extruder)] * steps_to_mm[E_AXIS_N(last_extruder)]);
       last_extruder = extruder;
     }
   #endif

Marlin/src/module/planner.h

@@ -866,7 +866,7 @@ class Planner {
         #define GET_MAX_E_JERK(N) SQRT(SQRT(0.5) * junction_deviation_mm * (N) * RECIPROCAL(1.0 - SQRT(0.5)))
         #if ENABLED(DISTINCT_E_FACTORS)
           for (uint8_t i = 0; i < EXTRUDERS; i++)
-            max_e_jerk[i] = GET_MAX_E_JERK(settings.max_acceleration_mm_per_s2[E_AXIS + i]);
+            max_e_jerk[i] = GET_MAX_E_JERK(settings.max_acceleration_mm_per_s2[E_AXIS_N(i)]);
         #else
           max_e_jerk = GET_MAX_E_JERK(settings.max_acceleration_mm_per_s2[E_AXIS]);
         #endif