The bow must be energized to the same power each time. Inconsistent drawing and anchoring of the bow can cause high or low shots, depending on how far the bow is stretched.
The correct way to load the bow is:
1) The bow arm must be stretched out to full extension. Only full extension is consistent. Bending the elbow varies because of draw pressures and therefore is not repeatable.
2) The middle finger of the draw hand must come level with the
face anchor. It must not be a bit past or before the anchor point. For
each inch we draw a bow the weight increases 2.5 to 3 lbs. For example
if we let go at 27 in. one shot and 29 in. the next, there is a 6 lb.
difference in weight. This is a high shot and a low shot because of a
variance in pressure even if the aim is perfect. The face anchor is not
from whence we aim but is the draw check that gives a repeatable
distance between bow hand and string hand.
This repeatable distance allows us to load the bow with the same energy.
3) The final step is, as our rotational draw brings the arrow
nock under the eye, our back tension takes effect. My shoulder blades
come together and my back muscles pull the shoulder and string elbow
back all stretched out on the line of force. This squeezing together
of the back muscles also causes the chest to come forward a bit, which
is where the saying of," Being in the bow," comes from. Now my bow arm
is extended, my draw is checked, my string elbow is stretched out
behind me, the spring is loaded.
To sum this up in simple terms the bow hand must be fully extended and the string elbow all the way back. If this distance varies whatsoever it's a miss.
These three steps will ensure your arrow goes the same distance at the same height.