Not all ducts are created equal. They come in different configurations, flexible, metal and building cavity are the most common. They are installed differently in different climates. This is mostly dependent on local practice rather then best practice.
One thing they all have in common is the requirement they be sealed to stop air leakage.
Common duct tape is, nor never has been acceptable to seal duct connections or leaks.
For new construction ACCA Manual D is recommended for determining the design of air distribution systems.
This video will provide guidelines for sealing existing ducts to improve an existing air distribution system.Manual D http://www.manuald.com/