Some pics of one of my projects, wing ribs for an RC sailplane... These are relatively small parts, less than 6"x1/2" for the largest. The smallest steps you see in the part, are around .020". The primary notch in the middle, where they are lined up on the ruler in one pic, has a tolerance of +/- .003 as cut, compared to the CAD drawing they came from. This is in balsa, using a .031" endmill.
Machine is a Probotix Comet, and I use Fusion360 for CAD/CAM. I know Probotix has an option for 4th axis, not sure on the tolerance differences when using that vs the standard 3 axis.