It depends on the offset of the grid.
Kill me now. LOL. My guess was that the embark region is an 8x8 of tiles
2x2, so that a move of one tile
2x2 is two clicks of movement u-m/h-k, which would keep me on the grid. I'm not assuming that is correct, nor that my description makes sense. From that I'm guessing that I have a map that is 2x2 of tiles
2x2 if and only if I move my embark square in even steps in the region. Again, I'm guessing about that. My Dwarven Geometry* locates 16 centers of 16 squares, but my foundation isn't bedrock.
To get this think about the possibility of the centre 2x2 squares being the larger cane-bearing square.... My limited experience in finding candy-canes suggests that the actual cane square is further divided into a 2x2 square.... These smaller squares (64 in total on a 4x4 embark)....
Okay, that's still better than completely random, assuming the center-of-the-square thing is still correct. I've seen it scattered about forums, the wiki, and the reddit threads, but we'll have to see how it goes.
I set up my grid, mined it out -- thank goodness for macros -- and drilled down dead nuts into a candy cane. It's hard to argue that n=1 is a good sample set. My grid is easy to subdivide, my pop has a soft cap of 15, my visitors are capped, my invaders are capped, I'm mining as little as possible, and I'm not collecting tons of stuff, so hopefully my fps will stay high.
I can't keep track of where things are nor can I picture the geography of the magma sea, so the grid is my main hope of sanity. Like gold, the stuff I'm looking for is basically useless; if I can't make kit for 15 military dwarves, now 18 when the kids grow up, what use is it? But finding it is an itch I must scratch. Gods, friends, drink, and a little work seem to make for a happy fort. Adam Smith would be proud.
*Have you read "Taxicab Geometry"? Construct a circle in Dwarven Geometry, i.e. the set of points equidistant from a center point. Dwarven eyes may be round to them, but to us they look square. Kinda creepy when you think about it.