Backing up issues ONLY involve the add on friction sway bars. If you have a hitch with engineered built in sway control, you don't have to worry about backing. End of story.
Lynnmore wants you to believe that it is important to reduce friction when towing in wet conditions. I can tell you from first hand experience that my Equalizer can't seem to tell the difference. I have towed two different trailers well over 50K miles with an Equalizer. Towed in rain, torrential at times, and gone uphill and down, into the wind and with the wind and have never had any trouble or sensed any sway. If you are using an add on friction bar, do you have to pull over and adjust your friction when it starts to rain? How much should you increase the friction? One full turn, or two or...? Or, should you decrease the friction? Again, one turn or two? I find all of this rather silly. Wet pavement does reduce friction between the rubber and the road. Does this alone cause increased trailer sway? And if so, how would your adjustments to your sway bar prevent this?
I have a relative that tows a pretty good sized trailer with a small truck. He uses an add on sway bar. When I asked him if he had any trouble with it he told me, "I usually don't use it. I will attach it if I think I might need it". Yeah, somehow he can predict when a sway condition will pop up. I guess that is similar to changing it when it rains. How much rain, how long will it be raining? Should I change it right now, or can I wait? Hmmmm....