Need more info, what fish are you targeting, how are you fishing, what river. Typically six is a little light for a mainline, some folks use six for leader in low water conditions when targeting steelhead. Big rivers with current require heavier line. Kings require heavier line. I use 12 main and 10 leader for steelhead in the winter, 10 main and 8 leader for summerruns. for kings you should use at least 18 main 15 leader. Alot of variables influence line selection.