I too seldom used it, once, but now as my eyes get older I find I use it almost continually when driving after dark (not that I go out much after dark if I can avoid it).
It is useless during the day in the dipped position. In fact, when I was learning to drive the bus I used to leave my car interior mirror dipped to reinforce the habit of moving my head to use the exterior mirrors. Must have worked because I passed.