diff --git a/Marlin/src/inc/Conditionals_post.h b/Marlin/src/inc/Conditionals_post.h
index c50480b971..15a3e1e548 100644
--- a/Marlin/src/inc/Conditionals_post.h
+++ b/Marlin/src/inc/Conditionals_post.h
@@ -263,7 +263,7 @@
    * Advance calculated values
    */
   #if ENABLED(ADVANCE)
-    #define EXTRUSION_AREA (0.25 * (D_FILAMENT) * (D_FILAMENT) * M_PI)
+    #define EXTRUSION_AREA CIRCLE_CIRC(0.5 * D_FILAMENT)
     #define STEPS_PER_CUBIC_MM_E (axis_steps_per_mm[E_AXIS_N] / (EXTRUSION_AREA))
   #endif
 
@@ -826,7 +826,10 @@
   #define ABL_PLANAR (ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_3POINT))
   #define ABL_GRID   (ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR))
   #define HAS_ABL    (ABL_PLANAR || ABL_GRID || ENABLED(AUTO_BED_LEVELING_UBL))
-  #define HAS_LEVELING          (HAS_ABL || ENABLED(MESH_BED_LEVELING))
+  #define HAS_LEVELING  (HAS_ABL || ENABLED(MESH_BED_LEVELING))
+  #define HAS_AUTOLEVEL (HAS_ABL && DISABLED(PROBE_MANUALLY))
+  #define OLDSCHOOL_ABL (HAS_ABL && DISABLED(AUTO_BED_LEVELING_UBL))
+  #define HAS_MESH   (ENABLED(AUTO_BED_LEVELING_BILINEAR) || ENABLED(AUTO_BED_LEVELING_UBL) || ENABLED(MESH_BED_LEVELING))
   #define PLANNER_LEVELING      (ABL_PLANAR || ABL_GRID || ENABLED(MESH_BED_LEVELING) || UBL_DELTA)
   #define HAS_PROBING_PROCEDURE (HAS_ABL || ENABLED(Z_MIN_PROBE_REPEATABILITY_TEST))
   #if HAS_PROBING_PROCEDURE
diff --git a/Marlin/src/inc/MarlinConfig.h b/Marlin/src/inc/MarlinConfig.h
index 847562b0de..10df8cb224 100644
--- a/Marlin/src/inc/MarlinConfig.h
+++ b/Marlin/src/inc/MarlinConfig.h
@@ -23,18 +23,25 @@
 #ifndef MARLIN_CONFIG_H
 #define MARLIN_CONFIG_H
 
-#include "macros.h"
-#include "src/HAL/HAL.h"
-#include "boards.h"
+#include "../core/boards.h"
+#include "../core/macros.h"
 #include "Version.h"
-#include "Configuration.h"
+#include "../config/Configuration.h"
 #include "Conditionals_LCD.h"
-#include "Configuration_adv.h"
-#include "pins.h"
+#include "../config/Configuration_adv.h"
+#include "../HAL/HAL.h"
+#include "../pins/pins.h"
 #if defined(ARDUINO_ARCH_AVR) && !defined(USBCON)
   #define HardwareSerial_h // trick to disable the standard HWserial
 #endif
 #include "Conditionals_post.h"
 #include "SanityCheck.h"
 
+// Include all core headers
+#include "../core/enum.h"
+#include "../core/language.h"
+#include "../core/types.h"
+#include "../core/utility.h"
+#include "../core/serial.h"
+
 #endif // MARLIN_CONFIG_H
diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index 151c1d1f30..2239e54776 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -301,7 +301,7 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE && Y_MAX_LENGTH >= Y_BED_SIZE,
     #error "BABYSTEPPING is not implemented for SCARA yet."
   #elif ENABLED(DELTA) && ENABLED(BABYSTEP_XY)
     #error "BABYSTEPPING only implemented for Z axis on deltabots."
-  #elif ENABLED(BABYSTEP_ZPROBE_OFFSET) &&  ENABLED(MESH_BED_LEVELING)
+  #elif ENABLED(BABYSTEP_ZPROBE_OFFSET) && ENABLED(MESH_BED_LEVELING)
     #error "MESH_BED_LEVELING and BABYSTEP_ZPROBE_OFFSET is not a valid combination"
   #elif ENABLED(BABYSTEP_ZPROBE_OFFSET) && !HAS_BED_PROBE
     #error "BABYSTEP_ZPROBE_OFFSET requires a probe."
@@ -643,12 +643,10 @@ static_assert(1 >= 0
   /**
    * Require some kind of probe for bed leveling and probe testing
    */
-  #if HAS_ABL
-    #if ENABLED(AUTO_BED_LEVELING_UBL)
-      #error "Unified Bed Leveling requires a probe: FIX_MOUNTED_PROBE, BLTOUCH, SOLENOID_PROBE, Z_PROBE_ALLEN_KEY, Z_PROBE_SLED, or Z Servo."
-    #else
-      #error "Auto Bed Leveling requires one of these: PROBE_MANUALLY, FIX_MOUNTED_PROBE, BLTOUCH, SOLENOID_PROBE, Z_PROBE_ALLEN_KEY, Z_PROBE_SLED, or a Z Servo."
-    #endif
+  #if ENABLED(AUTO_BED_LEVELING_UBL)
+    #error "Unified Bed Leveling requires a probe: FIX_MOUNTED_PROBE, BLTOUCH, SOLENOID_PROBE, Z_PROBE_ALLEN_KEY, Z_PROBE_SLED, or Z Servo."
+  #elif HAS_ABL
+    #error "Auto Bed Leveling requires one of these: PROBE_MANUALLY, FIX_MOUNTED_PROBE, BLTOUCH, SOLENOID_PROBE, Z_PROBE_ALLEN_KEY, Z_PROBE_SLED, or a Z Servo."
   #endif
 
 #endif
@@ -918,10 +916,11 @@ static_assert(1 >= 0
   #error "TEMP_SENSOR_0 is required."
 #endif
 
-#if HOTENDS > 1 || ENABLED(HEATERS_PARALLEL)
-  #if !HAS_HEATER_1
-    #error "HEATER_1_PIN not defined for this board."
-  #endif
+// Pins are required for heaters
+#if ENABLED(HEATER_0_USES_MAX6675) && !(defined(MAX6675_SS) && MAX6675_SS >= 0)
+  #error "MAX6675_SS (required for TEMP_SENSOR_0) not defined for this board."
+#elif (HOTENDS > 1 || ENABLED(HEATERS_PARALLEL)) && !HAS_HEATER_1
+  #error "HEATER_1_PIN not defined for this board."
 #endif
 
 #if HOTENDS > 1
@@ -1297,4 +1296,4 @@ static_assert(COUNT(sanity_arr_2) <= XYZE_N, "DEFAULT_MAX_FEEDRATE has too many
 static_assert(COUNT(sanity_arr_3) <= XYZE_N, "DEFAULT_MAX_ACCELERATION has too many elements.");
 
 
-#include "src/HAL/HAL_SanityCheck.h"  // get CPU specific checks
+#include "../HAL/HAL_SanityCheck.h"  // get CPU specific checks