Agree it doesn't do much, but if you wind on a decent amount it's useful. Like someone else above I tend to find ours has been left too far to the right after someone doing circuits.
I do trim it as part of my general cleaning up/sorting routine on long cruise legs, along with trying to lean a bit more scientifically, to get best performance. (And also on long climbs, if I'm heading for what we here call the stratosphere, i.e. anything above FL40!)
Tim