:art: Misc. code cleanup

Marlin/src/core/serial.h

 #define _SEP_N_P_REF()            _SEP_N_P
 #define _SEP_1_P(s)               serialprintPGM(s);
 #define _SEP_2_P(s,v)             serial_echopair_PGM(s,v);
-#define _SEP_3_P(s,v,V...)        _SEP_2_P(s,v); DEFER(_SEP_N_P_REF)()(TWO_ARGS(V),V);
+#define _SEP_3_P(s,v,V...)        _SEP_2_P(s,v); DEFER2(_SEP_N_P_REF)()(TWO_ARGS(V),V);
 #define SERIAL_ECHOPAIR_P(V...)   do{ EVAL(_SEP_N_P(TWO_ARGS(V),V)); }while(0)
 
 // Print up to 20 pairs of values followed by newline. Odd elements must be PSTR pointers.
 #define _SELP_N_P_REF()           _SELP_N_P
 #define _SELP_1_P(s)              { serialprintPGM(s); SERIAL_EOL(); }
 #define _SELP_2_P(s,v)            { serial_echopair_PGM(s,v); SERIAL_EOL(); }
-#define _SELP_3_P(s,v,V...)       { _SEP_2_P(s,v); DEFER(_SELP_N_P_REF)()(TWO_ARGS(V),V); }
+#define _SELP_3_P(s,v,V...)       { _SEP_2_P(s,v); DEFER2(_SELP_N_P_REF)()(TWO_ARGS(V),V); }
 #define SERIAL_ECHOLNPAIR_P(V...) do{ EVAL(_SELP_N_P(TWO_ARGS(V),V)); }while(0)
 
 #ifdef AllowDifferentTypeInList

Marlin/src/feature/dac/dac_mcp4728.cpp

 }
 
 /**
- * Write all input resistor values to EEPROM using SequencialWrite method.
+ * Write all input resistor values to EEPROM using SequentialWrite method.
  * This will update both input register and EEPROM value
  * This will also write current Vref, PowerDown, Gain settings to EEPROM
  */

Marlin/src/feature/joystick.cpp

     xyz_float_t move_dist{0};
     float hypot2 = 0;
     LOOP_XYZ(i) if (norm_jog[i]) {
-      move_dist[i] = seg_time * norm_jog[i] *
-        #if ENABLED(EXTENSIBLE_UI)
-          manual_feedrate_mm_s[i];
-        #else
-          planner.settings.max_feedrate_mm_s[i];
-        #endif
+      move_dist[i] = seg_time * norm_jog[i] * TERN(EXTENSIBLE_UI, manual_feedrate_mm_s, planner.settings.max_feedrate_mm_s)[i];
       hypot2 += sq(move_dist[i]);
     }
 

Marlin/src/gcode/motion/M290.cpp

       const float offs = constrain(parser.value_axis_units(Z_AXIS), -2, 2);
       babystep.add_mm(Z_AXIS, offs);
       #if ENABLED(BABYSTEP_ZPROBE_OFFSET)
-        if (!parser.seen('P') || parser.value_bool()) mod_probe_offset(offs);
+        if (parser.boolval('P', true)) mod_probe_offset(offs);
       #endif
     }
   #endif

Marlin/src/module/delta.cpp

   // Do this here all at once for Delta, because
   // XYZ isn't ABC. Applying this per-tower would
   // give the impression that they are the same.
-  LOOP_XYZ(i) set_axis_is_at_home((AxisEnum)i);
+  LOOP_ABC(i) set_axis_is_at_home((AxisEnum)i);
 
   sync_plan_position();
 

Marlin/src/module/settings.cpp

     {
       _FIELD_TEST(tmc_stepper_current);
 
-      tmc_stepper_current_t tmc_stepper_current = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+      tmc_stepper_current_t tmc_stepper_current{0};
 
       #if HAS_TRINAMIC_CONFIG
         #if AXIS_IS_TMC(X)
       _FIELD_TEST(tmc_hybrid_threshold);
 
       #if ENABLED(HYBRID_THRESHOLD)
-       tmc_hybrid_threshold_t tmc_hybrid_threshold = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+        tmc_hybrid_threshold_t tmc_hybrid_threshold{0};
         #if AXIS_HAS_STEALTHCHOP(X)
           tmc_hybrid_threshold.X = stepperX.get_pwm_thrs();
         #endif
             EEPROM_READ(dummyf);
           #endif
         #else
-          for (uint8_t q = 4; q--;) EEPROM_READ(dummyf);
+          for (uint8_t q = XYZE; q--;) EEPROM_READ(dummyf);
         #endif
 
         EEPROM_READ(TERN(CLASSIC_JERK, dummyf, planner.junction_deviation_mm));
           const xyz_float_t &backlash_distance_mm = backlash.distance_mm;
           const uint8_t &backlash_correction = backlash.correction;
         #else
-          float backlash_distance_mm[XYZ];
+          xyz_float_t backlash_distance_mm;
           uint8_t backlash_correction;
         #endif
         #if ENABLED(BACKLASH_GCODE) && defined(BACKLASH_SMOOTHING_MM)

Marlin/src/module/stepper.h

         #ifndef PWM_MOTOR_CURRENT
           #define PWM_MOTOR_CURRENT DEFAULT_PWM_MOTOR_CURRENT
         #endif
-        #define MOTOR_CURRENT_COUNT 3
+        #define MOTOR_CURRENT_COUNT XYZ
       #elif HAS_MOTOR_CURRENT_SPI
         static constexpr uint32_t digipot_count[] = DIGIPOT_MOTOR_CURRENT;
         #define MOTOR_CURRENT_COUNT COUNT(Stepper::digipot_count)

Marlin/src/module/tool_change.cpp

 
   void move_extruder_servo(const uint8_t e) {
     planner.synchronize();
-    #if EXTRUDERS & 1
-      if (e < EXTRUDERS - 1)
-    #endif
-    {
+    if ((EXTRUDERS & 1) && e < EXTRUDERS - 1) {
       MOVE_SERVO(_SERVO_NR(e), servo_angles[_SERVO_NR(e)][e & 1]);
       safe_delay(500);
     }