Business management deliver in 12hrs

This assignment has three parts: 

1. In your experience, have you found an effective decision making process useful in all situations?  Explain why or why not.  
2. How do you see a decision support system aiding business?  How can it be detrimental?  
3. Which one of the three: Decision Support, Executive Support and Group decision-support systems do you believe is more useful for an organization and why?