1. If you catch on thick fishing lines or braids - it is better to always install leashes. If small fishing lines (less than 0.14), then not necessary. The optimal leash is “the less the better”, but in order not to lose tackle in strength, it is better to put about 1/3 lower than the strength of the main fishing line2. As a rule, predatory fish are less careful and less demanding on leashes, but among them there are also cautious species, such as trout. In addition, the trophy specimens are all careful. Therefore, it’s better to always use leashes,sorry for google translator