6+ ft. leaders are commonly used by guys attempting to 'floss' hook fish. It's also called lining - drifting extra long leaders thru schools of fish until the leader goes into one with an open mouth and the leader draws thru the mouth commonly hooking it on the outside of the jaw. This is illegal snagging if you keep such hooked fish; and the gammies are tuning into it more and citing guys for it. If you turn lose fish hooked on the outside of the jaw you won't be busted or ridiculed. I see no gin-clear water situation that calls for driftfishing leader any longer than 4 ft. max! Beyond that length the legit biting fish have much more time to feel the hook and spit it out before the long leader de-slacks for you to feel the bite and set the hook. As for murky water, you will be more successful driftfishing with leaders a couple ft. long or so (20" to 30") than 3 ft. to 4 ft. leaders; for the same reason - the leader slack beyond the weight de-slacks quicker with the shorter leader enabling a quicker bite detection and hookset. The soft muted ticking of lead is more of a curiosity attractor than a spooking deal, and using slinky leads don't make noise or distract fish when there is any water color; light amount or murkier.