IIRC it triggered on speed and only scheduled between 25,45,(63/67) something in the back of my mind tells me it might also have gone to 58, someone certainly fitted a fatigue meter for 58 so it must have been there for a reason.
The problem was that once the movement had been triggered then it would complete before any further movement was possible so if, for instance, you were in 45 wing and accelerated beyond the trigger point the wings would begin to move to 67. Lets say you then immediately roll and pull hard into a turn bleeding the speed off, the wings will merrily continue to move to 67 before deciding that actually you did want 45 and starting their sweep forward again. By this point you had completed your turn, rolled wings level and accelerated and the wing moved back to 67 yet again.
The thinking was that by having it manually operated you could "think ahead" and know if moving the wings now was a good idea or not.