When an arrow is properly tuned for a bow, the bare shaft will shoot straight. I can group my well-tuned bare shafts with my fletched arrows at 30 yards. I wouldn't keep a bow if it won't do that. Some bows won't, because they are not tillered correctly, or are tillered to shoot from an elevated rest, so bare shafts won't fly well from the shelf. All of the well-known brands of laminated-wood bows that are designed to be shot from the shelf should tune fine, and bows that are designed to be shot from an elevated rest will tune fine if they're shot from an elevated rest.
You generally start with a high nock point, maybe 3/4", and gradually lower it until the bare shaft has a minimum amount of nock-high flight. Sometimes all nock-high can't be eliminated, and it is inadvisable to lower the nock point any further once the minimum is achieved, as the arrow may start hitting the shelf. A little nock-high is fine so long as the bare shaft groups with the fletched arrows.
Then you work on arrow spine to reduce nock-left or nock-right flight. If the bare shaft is flying nock-left (hitting the target to the right of the fletched arrows) then the spine is too weak, and vice-versa. Sometimes if this is extreme, the bare shaft will miss the target or hit it sideways, and so spine will have to be changed before you can accurately set the nock point. However, if it is within reason, you can either choose an arrow with a different spine, or you can shoot the same arrow with a shorter length to increase spine, or a longer length to decrease spine. Or, you can increase the point weight to decrease spine, or decrease point weight to increase the spine (vice-versa for adding weight to the back of the arrow).
Once you start shooting with a well-tuned arrow, you won't want to shoot with anything less.