I use braid for everything, but only tie a leader for certain applications. When fishing moving water, I always tie a leader because it allows the bait so sink better, since braid floats. When fishing heavy cover I tie braid directly to the bait. For jerkbaits, plastics, and finesse jigs I always tie a leader. For topwaters like frogs, I tie directly to braid. While many say using a flouro leader for poppers and spook type baits will damage the action, because it sinks faster than mono,I still use flouro...not mono. If the fish are active I will tie braid directly to the bait, but when the fish are keying to topwater, but not extremely active I like using the flouro leader beacause I will often deadstick the baits on top. Either way, I am not totally convinced that a leader helps any, other than in moving water. I fished without a leader for many years and caught just as many fish. I always tie a uni to uni knot, and have yet to have it fail on a fish or snag. My palomar to the bait breaks before the uni does almost always. Regardless, you will hook way more fish using braid than you will using mono.