I can say that it’s within the range that many people have experienced, including myself. The ultimate goal (as I understand it) is 0.5 mm (1/64-inch) accuracy across the entire sheet of plywood. I don’t know if anyone is achieving that, particularly in the bottom corners. But to put your question into perspective, if a cut is 1/16-inch too long, it could in be that the start point was 1/32-inch too high and the stop point 1/32-inch too low. If that’s the case, that’s pretty darn close to the 1/64-inch goal. Of course, it could be that the start point was 1/16-inch too high and the stop point was dead on accurate, or vice versa.
If the real question is whether or not you can improve upon it, that really depends upon how accurate you built your machine and how accurately the model used by the controller reflects the real world. See this post relating to sources of errors:
There’s lots of room for error and I suspect they all need to be eliminated to achieve the ultimate accuracy goal. I don’t know if that is universally feasible with a hand-assembled system unless we can find a way to compensate for “less-than-perfect” construction.