The basic answer is that you should use a leader 90 percent of the time when fishing with braided line. Braid provides several advantages, including increased casting distance, strength, and sensitivity. It also helps prevent entanglement in underwater vegetation. The other 10 percent of the time, you should use a straight line. A straight line is easier to cast than a braid, and it's better for keeping track of large fish such as bass or trout. However, when using a straight line, you need to be careful not to drift into unwanted areas like shallow water or reefs. If this happens, your line will wear out before you catch anything important. The length of time you should keep a leader on a braided line depends on what kind of game you're after. If you're simply looking for fun and exercise, then a short leader is sufficient. But if you want to be able to pull in big fish, then you should use a leader at least as long as I described above. The more times you cross-over your line, the less likely you are to catch something!