With my 30" draw length, I shoot 32" arrows instead of 31" arrows and I'll explain why below.
When I was 18 years old, that was when I stopped growing and I had a 30" draw length. I shot 31" arrows. This gave me 1" of clearance between the back of a broadhead and the front of the shelf. I also shoot off the shelf.
When I was 23 years old, I drew down on the biggest racked whitetail buck deer I had ever seen. It had at least 16 points and the rack was heavy beamed. I was shooting a 3 blade broadhead and the broadhead was mounted "Y" shaped.
My left hand that grips the bow, the knuckle on my index finger sticks out 1/2" in front of the shelf. That left me, at the time, with 1/2" of clearance between my knuckle and the back of that very sharp 3 blade broadhead shooting a 31" arrow.
I got so excited at seeing that buck at around 15 yards, I overdrew past my anchor point. The back of the broadhead where the the bottom blade was vertical, sliced my knuckle to the bone.
Suffice to say, I didn't get the shot away since I dropped the bow when I felt the pain. I did get 2 stitches at the emergency room though.
After that humbling and painful experience, from then on I've always shot 32" arrows because I want 1 1/2" clearance between the back of any broadhead and the knuckle on my left index finger.
Like the old saying goes, "Pain........is an excellent teacher".