It's good to pay attention to details and if keeping your arrow weights within a +/- 1.0 grain range helps your confidence, I would say keep doing it. For those of you who don't, however, 2 grains difference between arrows will absolutely not result in a measureable difference in the impact point even shot from a shooting machine let alone an archer so if you are not so inclined to be so maticulous I wouldn't worry about it.