1. Bulk Delete Operations
bulk_delete() or queryset .delete() operations are not captured
Only individual model .delete() calls trigger the post_delete signal

2. Pre-Event Signals
pre_save - fired before a model is saved
pre_delete - fired before a model is deleted
pre_m2m_changed - fired before M2M relationships change

3. Other Bulk Operations
bulk_upsert() (if using Django 4.2+)
Raw SQL operations that bypass the ORM entirely

4. Database-Level Operations
Direct database operations using connection.cursor()
Operations using Django's extra(), raw(), or extra_tables

5. Transaction Rollbacks
Changes made during transactions that are later rolled back