When to careful while Testing ?

Make sure that never ever perform testing or be careful (cross check / reverify with someone senior) when I have :

• Lack of domain knowledge, experience.
• Tired.
• Time Pressure.
• Careless Mood.
• Misunderstood the requirments.
• Dealing with puzzled technical/buisnuiss problem.
• Bigger codebase.
• Multiple system interactions.

Why Careful ?

Science says our brains can only deal with a reasonable amount of complexity or change, when asked to deal with more our brains may not process the information we have correctly.