Back in the olden days I was a heavy weapons infantryman. A 11C3. a mortar man. I was also a Davy Crocket Gunner and thus the MOS 11C3(N) we ROUTINELY used 8 didgit grid coordinates which got withing 10 meters for Mortar firing and adjusting on the initial call. Also as pilots we were taught land navigation using 8 didgit coordinates. Once we started flying AFTER FLIGHT SCHOOL we used the 6 digit coordinate for simplicity.
BT