That is the key to taking a bad day, and not making it worse. If you know the exact distance to your nocking point, you could get dialed in very quickly. The biggest problem will happen if your old string had stretched a lot. Your bow may be shooting a different poundage with a new, shorter string. Personally, I take monthly measurement of my axel to axel length and the distance to my nocking point. If my a to a has changed, I take the string off and put a twist or two in it. When I change strings (twice a year), I frequently don't have to touch a thing after I use these measurements to set up the new string. This is often enough to get the bow shooting exactly as before. If not, the adjustments are minor.