4LO - Another don't leave home without it tip. Particularly for larger trailers.
When maneuvering a trailer at low speeds, perhaps to get parked on site or onto levelers - flip that low range switch. It'll enable a level of control and precision that can't be had without it. I find it immensely helpful to place my trailer exactly where I want it. Regardless of grade, berms, bumps. Fractional inch precision to get it onto my Anderson curved levelers. No need to load up the torque converter and allows the engine to idle its way to the goal. Besides, it's good to exercise the mechanism and what better way to leverage it.
There's a nice interaction on the LX with WD bars as well. Switching to low range will automatically put the system in AHC high - which relaxes the WD bars. I'll usually throw it in low range as soon as I get to a campground, and the relaxed WD bars help traverse the often uneven terrain with less strain and hitch groan. Then the WD bar are relaxed and almost ready to be removed if I unhitch.