diff --git a/src/hotspot/share/gc/shenandoah/heuristics/shenandoahOldHeuristics.cpp b/src/hotspot/share/gc/shenandoah/heuristics/shenandoahOldHeuristics.cpp
index cf1a76ff4ff..2d0bbfd5e4a 100644
--- a/src/hotspot/share/gc/shenandoah/heuristics/shenandoahOldHeuristics.cpp
+++ b/src/hotspot/share/gc/shenandoah/heuristics/shenandoahOldHeuristics.cpp
@@ -639,12 +639,9 @@ bool ShenandoahOldHeuristics::should_resume_old_cycle() {
 bool ShenandoahOldHeuristics::should_start_gc() {
 
   const ShenandoahHeap* heap = ShenandoahHeap::heap();
-  if (_old_generation->is_doing_mixed_evacuations()) {
-    // Do not try to start an old cycle if we are waiting for old regions to be evacuated (we need
-    // a young cycle for this). Note that the young heuristic has a feature to expedite old evacuations.
-    // Future refinement: under certain circumstances, we might be more sophisticated about this choice.
-    // For example, we could choose to abandon the previous old collection before it has completed evacuations.
-    log_debug(gc)("Not starting an old cycle because we are waiting for mixed evacuations");
+  if (!_old_generation->is_idle()) {
+    // Do not try to start an old cycle if old-gen is marking, doing mixed evacuations, or coalescing and filling.
+    log_debug(gc)("Not starting an old cycle because old gen is busy");
     return false;
   }
 
diff --git a/src/hotspot/share/gc/shenandoah/heuristics/shenandoahYoungHeuristics.cpp b/src/hotspot/share/gc/shenandoah/heuristics/shenandoahYoungHeuristics.cpp
index ba09eeb8794..3aca436104b 100644
--- a/src/hotspot/share/gc/shenandoah/heuristics/shenandoahYoungHeuristics.cpp
+++ b/src/hotspot/share/gc/shenandoah/heuristics/shenandoahYoungHeuristics.cpp
@@ -120,6 +120,7 @@ bool ShenandoahYoungHeuristics::should_start_gc() {
       if (old_time_elapsed < ShenandoahMinimumOldTimeMs) {
         // Do not decline_trigger() when waiting for minimum quantum of Old-gen marking.  It is not at our discretion
         // to trigger at this time.
+        log_debug(gc)("Young heuristics declines to trigger because old_time_elapsed < ShenandoahMinimumOldTimeMs");
         return false;
       }
     }
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahRegulatorThread.cpp b/src/hotspot/share/gc/shenandoah/shenandoahRegulatorThread.cpp
index bf309af9743..774c4f7d941 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahRegulatorThread.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahRegulatorThread.cpp
@@ -67,22 +67,18 @@ void ShenandoahRegulatorThread::regulate_young_and_old_cycles() {
           _global_heuristics->cancel_trigger_request();
         }
       } else {
-        if (_young_heuristics->should_start_gc()) {
-          // Give the old generation a chance to run. The old generation cycle
-          // begins with a 'bootstrap' cycle that will also collect young.
-          if (start_old_cycle()) {
-            log_debug(gc)("Heuristics request for old collection accepted");
-            _young_heuristics->cancel_trigger_request();
-            _old_heuristics->cancel_trigger_request();
-          } else if (request_concurrent_gc(_heap->young_generation())) {
-            log_debug(gc)("Heuristics request for young collection accepted");
-            _young_heuristics->cancel_trigger_request();
-          }
-        } else if (_old_heuristics->should_resume_old_cycle() || _old_heuristics->should_start_gc()) {
+        if (_old_heuristics->should_resume_old_cycle()) {
           if (request_concurrent_gc(_heap->old_generation())) {
             _old_heuristics->cancel_trigger_request();
             log_debug(gc)("Heuristics request to resume old collection accepted");
           }
+        } else if (start_old_cycle()) {
+          log_debug(gc)("Heuristics request for old collection accepted");
+          _young_heuristics->cancel_trigger_request();
+          _old_heuristics->cancel_trigger_request();
+        } else if (start_young_cycle()) {
+          log_debug(gc)("Heuristics request for young collection accepted");
+          _young_heuristics->cancel_trigger_request();
         }
       }
     } else if (mode == ShenandoahGenerationalControlThread::servicing_old) {