My draw is 29.5" and I cut my arrows to just under 30". At full draw, the tips and broadheads sit just a little past the midway point of the arrow shelf. This length works perfectly for me and I shoot standard diameter carbon arrows. Others prefer a longer arrow so that it extends well beyond the shelf.
I set up my arrows with a higher FOC and heavier total weight (over 480 grains), so that works out to a 300 spine which takes into account my 70lb draw weight. A longer arrow and I might be looking at a stiffer spine to avoid the thing from flopping in the air on its way to the target.
On another note, I fletch my arrows with a 3 degree helical configuration. Does wonders for stabilizing my fixed-blade broadheads.
I cut mine so they spine right and therefore tune perfectly. I have a 29 1/4" draw and shoot a 60lb Xcursion 6, I get perfect bare shaft arrow flight to 40 yards with a 29" c to c 300 spined Black Eagle Rampage with 177grs up front; 52grs for the insert and a 125gr head. Broadheads, fieldpoints, and bare shaft all hit to the same point of impact.