You can still get arrows to group at a given distance with a poor tune.
It just means they are doing the same thing during each shot -no more, no less.

While that sounds OK, the problem comes in when you change the distance to your target, like when hunting.
The arrow may be dead on at 20 yards, but may be high, low, left, or right at other ranges. If you always shoot at 20, you'll never see it. If they hit 2" left at one range, and 2" right at another, now we have 4" total error. Add that into possible maistakes in form for a given shot, and Murphy's law that seems to come into play when hunting, and you have shortened your effective range considerably.

Go with BG's suggestion.
The tuning guide is a great help.
If you have trouble with the Zipped PDF version, they can send you a hard copy.