SA = Satellite Accuracy.

The coordinates of a given physical location likely will be a bit different even if checked some several minutes later. If they were the same the next year it'd be a fluke is all. Unless the exact same satellites are in the exact same position and their calibration hasn't changed of course, but that'd be a bit like winning the lottery 2 years in a row to put it in perspective.

What about if you chose a starting spot which is reasonably accurately defined from year to year by finding it within a few metres by triangulation then used a dumpy level and laser measure for shooting the rest of the layout? Total outlay is only going to be several hundred bucks then.