Do I need a shock leader? In my opinion a Shock Leader is needed when using a braided main line. A shock leader will help you catch more fish surf fishing, pier fishing, or even fishing from a boat. I setup some line comparison tests to show the benefits of using a shock leader when using a braided main line.

Here is some extra info about how long and what pound test to use:
If you are using a shock leader to throw heavier weights than your mainline can handle the shock leader will need to wrap around your reels spool at least 5 to 10 times. But If your mainline can handle the weights that you are throwing you do not have to wrap the shock leader around the spool of your reel if you do not want to. I personally only use 6 to 8 feet of shock leader when surf fishing so when I cast the shock leader is not coming off of my spool. I do this to keep casting distance at a maximum. Deciding what pound test to use for a shock leader really just depends on what you are doing and personal preference. I personally use 20lb shock leader when surf fishing for Pompano because I can throw a 4oz weight all day long without breaking off. If using cut bait I will use 40lb or higher. The 10 pounds of line per ounce of weight rule is a poor guide to go by in my opinion. I suggest using the lightest pound test you can get away with. Good luck!

Shock leader for surf fishing
Shock leader to main line
Shock leader to braid