I carry mine all the time. Once we cut cross country to hit another trail in an area that's fairly straightforward - I could just barely see a prominent peak and kept it over my left shoulder as we wandered along through meadows, across bogs, creeks, deadfall, through blueberry thickets... every so often we stopped to check bearings. Unbeknownst to me this was making some of the non-orienteering members of the group nervous. They thought we were lost and trying to find our way.

I've also had occasion to map/compass to determine which trail is which at a junction. Signs vanish sometimes. While one can generally orient by the sun, sometimes it's cloudy....