Shooting wood or aluminum for practice or with blunts, I cut them short, and broadheads about 3/4 longer for my index finger. The shorts are 27.5" to the back of the head and serve as a draw check.
I understand why guys leave carbons long, but would use a lighter spine and cut them the same, IMO.
Howard Hill referred to the part of the arrow hanging over the rest as "dead wood". If you check photos you can see he drew the head onto the rest, except for broadheads which were cut to allow for the index finger. The elephant arrow was an exception, and was 41" for a reason.
Wood shafts are pretty spine specific, aluminum is somewhat the same and carbon much less. It is entirely up to you. If you lost an inch, then the draw weight is about 3+/- lbs less. You should determine if the arrow is still the correct spine, before cutting.