No need to back. They do require a bit of time but more importantly some axle movement to fully lock/unlock. Usually I hit the switch while approaching allowing about 5-10 feet for the light to go solid. Then when unlocking I just hit the switch and go - sometimes it takes a few feet to unload enough to unlock - especially if axle bound from trying to turn. I would say that if you need to turn tight so dont have the few feet to spare - rock back and forth to unbind and it should unlock pretty quick - i have had to do this when going from both locked to rear only - the fronts do bind more (as they are steering).
J Wm Bishop EA, ASADE
My greatest fear, is that when I die, my wife will sell my Jeep for what I have told her it's cost ...