If you believe that the spine of the arrow must be "correct", than you will need to leave the arrow long and put a ton of weight in the tip to "spine" the arrow correctly (dynamic spine). Of course only applies to the large diameter "Logs" that so many of us shoot inside.
If you believe that any arrow that is over spined is ok (under spined is not, but many of us believe that over spined is OK), than there is no reason to us a long arrow, unless....
If you shoot Arrow Dynamics Nitro Stingers or .395 Mags, than leaving them long will help keep from driving the arrows so deep that the taper of the shaft could cause you to loose possible points.
I hope that this give you some idea of what you can do. There is really no "set in stone" way of doing this so feel free to experiment and find out what works best for you.
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