We recommend a 6 for quick, accurate casting on lakes, fishing streamers, for bigger rivers where we might be fishing heavy nymphs, and for fishing in windy places like Tassie or New Zealand. A 6 weight is also perfect for fishing from a boat if that's your jam. If you could pick one line weight to learn to cast with, the 6 weight is the one... but equally it's a rod that will see a lot of fishing, as trout seem to love windy places...!