Several reasons I shortened my draw 1/2".

1. I believe I was slightly overdrawing for a few years
2. When shooting 3D and if getting tired during the last few targets I found myself creeping. That told me that my bow was set up incorrectly for draw length because my form was not good.
3. False sense of comfort at 30", shortening a 1/2" made me relaxed and comfy.
4. At my former draw length I was not always at a good hard stop at full draw, if that makes any sense.
5. After many years of shooting I contracted target panic and fought it off and on for several years. I feel my former draw contributed to me acquiring it. TP is now a thing of the past for me and I believe shortening my draw played a tiny part in the process of fighting through and ending it.
6. In some shooting situations, especially in a treestand at certain angles I found myself not locked in at full draw. To draw back at the bow's set draw length I was having to reach for a little more.....not good.