diff --git a/Marlin/src/module/stepper.cpp b/Marlin/src/module/stepper.cpp
index ae12f0b7f4..4872e98aa9 100644
--- a/Marlin/src/module/stepper.cpp
+++ b/Marlin/src/module/stepper.cpp
@@ -194,6 +194,10 @@ uint32_t Stepper::acceleration_time, Stepper::deceleration_time;
   uint8_t Stepper::steps_per_isr = 1; // Count of steps to perform per Stepper ISR call
 #endif
 
+#if DISABLED(OLD_ADAPTIVE_MULTISTEPPING)
+  hal_timer_t Stepper::time_spent_in_isr = 0, Stepper::time_spent_out_isr = 0;
+#endif
+
 #if ENABLED(FREEZE_FEATURE)
   bool Stepper::frozen; // = false
 #endif
@@ -614,27 +618,26 @@ void Stepper::set_directions() {
   TERN_(HAS_V_DIR, SET_STEP_DIR(V));
   TERN_(HAS_W_DIR, SET_STEP_DIR(W));
 
-  #if ENABLED(MIXING_EXTRUDER)
+  #if HAS_EXTRUDERS
      // Because this is valid for the whole block we don't know
      // what E steppers will step. Likely all. Set all.
     if (motor_direction(E_AXIS)) {
-      MIXER_STEPPER_LOOP(j) REV_E_DIR(j);
+      #if ENABLED(MIXING_EXTRUDER)
+        MIXER_STEPPER_LOOP(j) REV_E_DIR(j);
+      #else
+        REV_E_DIR(stepper_extruder);
+      #endif
       count_direction.e = -1;
     }
     else {
-      MIXER_STEPPER_LOOP(j) NORM_E_DIR(j);
+      #if ENABLED(MIXING_EXTRUDER)
+        MIXER_STEPPER_LOOP(j) NORM_E_DIR(j);
+      #else
+        NORM_E_DIR(stepper_extruder);
+      #endif
       count_direction.e = 1;
     }
-  #elif HAS_EXTRUDERS
-    if (motor_direction(E_AXIS)) {
-      REV_E_DIR(stepper_extruder);
-      count_direction.e = -1;
-    }
-    else {
-      NORM_E_DIR(stepper_extruder);
-      count_direction.e = 1;
-    }
-  #endif
+  #endif // HAS_EXTRUDERS
 
   DIR_WAIT_AFTER();
 }
@@ -1587,16 +1590,44 @@ void Stepper::isr() {
      */
     min_ticks = HAL_timer_get_count(MF_TIMER_STEP) + hal_timer_t(TERN(__AVR__, 8, 1) * (STEPPER_TIMER_TICKS_PER_US));
 
-    /**
-     * NB: If for some reason the stepper monopolizes the MPU, eventually the
-     * timer will wrap around (and so will 'next_isr_ticks'). So, limit the
-     * loop to 10 iterations. Beyond that, there's no way to ensure correct pulse
-     * timing, since the MCU isn't fast enough.
-     */
-    if (!--max_loops) next_isr_ticks = min_ticks;
+    #if ENABLED(OLD_ADAPTIVE_MULTISTEPPING)
+      /**
+       * NB: If for some reason the stepper monopolizes the MPU, eventually the
+       * timer will wrap around (and so will 'next_isr_ticks'). So, limit the
+       * loop to 10 iterations. Beyond that, there's no way to ensure correct pulse
+       * timing, since the MCU isn't fast enough.
+       */
+      if (!--max_loops) next_isr_ticks = min_ticks;
+    #endif
 
     // Advance pulses if not enough time to wait for the next ISR
-  } while (next_isr_ticks < min_ticks);
+  } while (TERN(OLD_ADAPTIVE_MULTISTEPPING, true, --max_loops) && next_isr_ticks < min_ticks);
+
+  #if DISABLED(OLD_ADAPTIVE_MULTISTEPPING)
+
+    // Track the time spent in the ISR
+    const hal_timer_t time_spent = HAL_timer_get_count(MF_TIMER_STEP);
+    time_spent_in_isr += time_spent;
+
+    if (next_isr_ticks < min_ticks) {
+      next_isr_ticks = min_ticks;
+
+      // When forced out of the ISR, increase multi-stepping
+      #if MULTISTEPPING_LIMIT > 1
+        if (steps_per_isr < MULTISTEPPING_LIMIT) {
+          steps_per_isr <<= 1;
+          // ticks_nominal will need to be recalculated if we are in cruise phase
+          ticks_nominal = 0;
+        }
+      #endif
+    }
+    else {
+      // Track the time spent voluntarily outside the ISR
+      time_spent_out_isr += next_isr_ticks;
+      time_spent_out_isr -= time_spent;
+    }
+
+  #endif // !OLD_ADAPTIVE_MULTISTEPPING
 
   // Now 'next_isr_ticks' contains the period to the next Stepper ISR - And we are
   // sure that the time has not arrived yet - Warrantied by the scheduler
@@ -2091,44 +2122,56 @@ hal_timer_t Stepper::calc_timer_interval(uint32_t step_rate) {
 
 // Get the timer interval and the number of loops to perform per tick
 hal_timer_t Stepper::calc_multistep_timer_interval(uint32_t step_rate) {
-  #if MULTISTEPPING_LIMIT == 1
 
-    // Just make sure the step rate is doable
-    NOMORE(step_rate, uint32_t(MAX_STEP_ISR_FREQUENCY_1X));
+  #if ENABLED(OLD_ADAPTIVE_MULTISTEPPING)
 
-  #else
+    #if MULTISTEPPING_LIMIT == 1
 
-    // The stepping frequency limits for each multistepping rate
-    static const uint32_t limit[] PROGMEM = {
-          (  MAX_STEP_ISR_FREQUENCY_1X     )
-        , (  MAX_STEP_ISR_FREQUENCY_2X >> 1)
-      #if MULTISTEPPING_LIMIT >= 4
-        , (  MAX_STEP_ISR_FREQUENCY_4X >> 2)
-      #endif
-      #if MULTISTEPPING_LIMIT >= 8
-        , (  MAX_STEP_ISR_FREQUENCY_8X >> 3)
-      #endif
-      #if MULTISTEPPING_LIMIT >= 16
-        , ( MAX_STEP_ISR_FREQUENCY_16X >> 4)
-      #endif
-      #if MULTISTEPPING_LIMIT >= 32
-        , ( MAX_STEP_ISR_FREQUENCY_32X >> 5)
-      #endif
-      #if MULTISTEPPING_LIMIT >= 64
-        , ( MAX_STEP_ISR_FREQUENCY_64X >> 6)
-      #endif
-      #if MULTISTEPPING_LIMIT >= 128
-        , (MAX_STEP_ISR_FREQUENCY_128X >> 7)
-      #endif
-    };
+      // Just make sure the step rate is doable
+      NOMORE(step_rate, uint32_t(MAX_STEP_ISR_FREQUENCY_1X));
 
-    // Find a doable step rate using multistepping
-    uint8_t multistep = 1;
-    for (uint8_t i = 0; i < COUNT(limit) && step_rate > uint32_t(pgm_read_dword(&limit[i])); ++i) {
-      step_rate >>= 1;
-      multistep <<= 1;
-    }
-    steps_per_isr = multistep;
+    #else
+
+      // The stepping frequency limits for each multistepping rate
+      static const uint32_t limit[] PROGMEM = {
+            (  MAX_STEP_ISR_FREQUENCY_1X     )
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(1)) >> 1)
+        #if MULTISTEPPING_LIMIT >= 4
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(2)) >> 2)
+        #endif
+        #if MULTISTEPPING_LIMIT >= 8
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(3)) >> 3)
+        #endif
+        #if MULTISTEPPING_LIMIT >= 16
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(4)) >> 4)
+        #endif
+        #if MULTISTEPPING_LIMIT >= 32
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(5)) >> 5)
+        #endif
+        #if MULTISTEPPING_LIMIT >= 64
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(6)) >> 6)
+        #endif
+        #if MULTISTEPPING_LIMIT >= 128
+          , (((F_CPU) / ISR_EXECUTION_CYCLES(7)) >> 7)
+        #endif
+      };
+
+      // Find a doable step rate using multistepping
+      uint8_t multistep = 1;
+      for (uint8_t i = 0; i < COUNT(limit) && step_rate > uint32_t(pgm_read_dword(&limit[i])); ++i) {
+        step_rate >>= 1;
+        multistep <<= 1;
+      }
+      steps_per_isr = multistep;
+
+    #endif
+
+  #elif MULTISTEPPING_LIMIT > 1
+
+    uint8_t loops = steps_per_isr;
+    if (MULTISTEPPING_LIMIT >= 16 && loops >= 16) { step_rate >>= 4; loops >>= 4; }
+    if (MULTISTEPPING_LIMIT >=  4 && loops >=  4) { step_rate >>= 2; loops >>= 2; }
+    if (MULTISTEPPING_LIMIT >=  2 && loops >=  2) { step_rate >>= 1; }
 
   #endif
 
@@ -2141,6 +2184,19 @@ hal_timer_t Stepper::calc_multistep_timer_interval(uint32_t step_rate) {
  * have been done, so it is less time critical.
  */
 hal_timer_t Stepper::block_phase_isr() {
+  #if DISABLED(OLD_ADAPTIVE_MULTISTEPPING)
+    // If the ISR uses < 50% of MPU time, halve multi-stepping
+    const hal_timer_t time_spent = HAL_timer_get_count(MF_TIMER_STEP);
+    #if MULTISTEPPING_LIMIT > 1
+      if (steps_per_isr > 1 && time_spent_out_isr >= time_spent_in_isr + time_spent) {
+        steps_per_isr >>= 1;
+        // ticks_nominal will need to be recalculated if we are in cruise phase
+        ticks_nominal = 0;
+      }
+    #endif
+    time_spent_in_isr = -time_spent;    // unsigned but guaranteed to be +ve when needed
+    time_spent_out_isr = 0;
+  #endif
 
   // If no queued movements, just wait 1ms for the next block
   hal_timer_t interval = (STEPPER_TIMER_RATE) / 1000UL;
diff --git a/Marlin/src/module/stepper.h b/Marlin/src/module/stepper.h
index 797a72791c..704805464c 100644
--- a/Marlin/src/module/stepper.h
+++ b/Marlin/src/module/stepper.h
@@ -212,12 +212,12 @@
   #error "Expected at least one of MINIMUM_STEPPER_PULSE or MAXIMUM_STEPPER_RATE to be defined"
 #endif
 
-// The loop takes the base time plus the time for all the bresenham logic for R pulses plus the time
-// between pulses for (R-1) pulses. But the user could be enforcing a minimum time so the loop time is:
+// The loop takes the base time plus the time for all the bresenham logic for 1 << R pulses plus the time
+// between pulses for ((1 << R) - 1) pulses. But the user could be enforcing a minimum time so the loop time is:
 #define ISR_LOOP_CYCLES(R) ((ISR_LOOP_BASE_CYCLES + MIN_ISR_LOOP_CYCLES + MIN_STEPPER_PULSE_CYCLES) * ((1UL << R) - 1) + _MAX(MIN_ISR_LOOP_CYCLES, MIN_STEPPER_PULSE_CYCLES))
 
 // Model input shaping as an extra loop call
-#define ISR_SHAPING_LOOP_CYCLES(R) (TERN0(HAS_SHAPING, ((ISR_LOOP_BASE_CYCLES) + TERN0(INPUT_SHAPING_X, ISR_X_STEPPER_CYCLES) + TERN0(INPUT_SHAPING_Y, ISR_Y_STEPPER_CYCLES)) << R))
+#define ISR_SHAPING_LOOP_CYCLES(R) (TERN0(HAS_SHAPING, (ISR_LOOP_BASE_CYCLES + TERN0(INPUT_SHAPING_X, ISR_X_STEPPER_CYCLES) + TERN0(INPUT_SHAPING_Y, ISR_Y_STEPPER_CYCLES)) << R))
 
 // If linear advance is enabled, then it is handled separately
 #if ENABLED(LIN_ADVANCE)
@@ -241,24 +241,17 @@
   #define ISR_LA_LOOP_CYCLES 0UL
 #endif
 
-// Now estimate the total ISR execution time in cycles given a step per ISR multiplier
-#define ISR_EXECUTION_CYCLES(R) (((ISR_BASE_CYCLES + ISR_S_CURVE_CYCLES + ISR_SHAPING_BASE_CYCLES + ISR_LOOP_CYCLES(R) + ISR_SHAPING_LOOP_CYCLES(R) + ISR_LA_BASE_CYCLES + ISR_LA_LOOP_CYCLES)) >> R)
+// Estimate the total ISR execution time in cycles given a step-per-ISR shift multiplier
+#define ISR_EXECUTION_CYCLES(R) ((ISR_BASE_CYCLES + ISR_S_CURVE_CYCLES + ISR_SHAPING_BASE_CYCLES + ISR_LOOP_CYCLES(R) + ISR_SHAPING_LOOP_CYCLES(R) + ISR_LA_BASE_CYCLES + ISR_LA_LOOP_CYCLES) >> R)
 
-// The maximum allowable stepping frequency when doing x128-x1 stepping (in Hz)
-#define MAX_STEP_ISR_FREQUENCY_128X ((F_CPU) / ISR_EXECUTION_CYCLES(7))
-#define MAX_STEP_ISR_FREQUENCY_64X  ((F_CPU) / ISR_EXECUTION_CYCLES(6))
-#define MAX_STEP_ISR_FREQUENCY_32X  ((F_CPU) / ISR_EXECUTION_CYCLES(5))
-#define MAX_STEP_ISR_FREQUENCY_16X  ((F_CPU) / ISR_EXECUTION_CYCLES(4))
-#define MAX_STEP_ISR_FREQUENCY_8X   ((F_CPU) / ISR_EXECUTION_CYCLES(3))
-#define MAX_STEP_ISR_FREQUENCY_4X   ((F_CPU) / ISR_EXECUTION_CYCLES(2))
-#define MAX_STEP_ISR_FREQUENCY_2X   ((F_CPU) / ISR_EXECUTION_CYCLES(1))
-#define MAX_STEP_ISR_FREQUENCY_1X   ((F_CPU) / ISR_EXECUTION_CYCLES(0))
+// The maximum allowable stepping frequency when doing 1x stepping (in Hz)
+#define MAX_STEP_ISR_FREQUENCY_1X ((F_CPU) / ISR_EXECUTION_CYCLES(0))
 
 // The minimum step ISR rate used by ADAPTIVE_STEP_SMOOTHING to target 50% CPU usage
 // This does not account for the possibility of multi-stepping.
-// Should a MULTISTEPPING_LIMIT of 1 should be required with ADAPTIVE_STEP_SMOOTHING?
-#define MIN_STEP_ISR_FREQUENCY (MAX_STEP_ISR_FREQUENCY_1X / 2)
+#define MIN_STEP_ISR_FREQUENCY (MAX_STEP_ISR_FREQUENCY_1X >> 1)
 
+// Number of axes that could be enabled/disabled. Dual/multiple steppers are combined.
 #define ENABLE_COUNT (NUM_AXES + E_STEPPERS)
 typedef bits_t(ENABLE_COUNT) ena_mask_t;
 
@@ -547,6 +540,10 @@ class Stepper {
       static uint8_t steps_per_isr;
     #endif
 
+    #if DISABLED(OLD_ADAPTIVE_MULTISTEPPING)
+      static hal_timer_t time_spent_in_isr, time_spent_out_isr;
+    #endif
+
     #if ENABLED(ADAPTIVE_STEP_SMOOTHING)
       static uint8_t oversampling_factor; // Oversampling factor (log2(multiplier)) to increase temporal resolution of axis
     #else