A good habit to get in when throwing the jig for snook (and other large gamefish like redfish and tarpon) is checking the leader very often; not just after catching a fish. Dragging the jig through rocky bottom and around bridge pilings can chafe a leader very quickly. And, it doesn't take much wear on a leader to lose a fish. Start with a long leader, check it often, re-tie when you see frays and chafing, and keep your odds up! In most jig situations the odds are in the fish's favor, don't give them anymore of an advantage than they already have!
Pro Tip- When you see ANY marks on flurocarbon leader it is time to re-tie! Not only is the strength compromised; when fluro becomes nicked or frayed in anyway it loses all of its invisibility properties.