Plus or minus 10, or 20 grains total, is a common standard. I always try to match for a 10 grain spread. In reality, at normal stick bow hunting ranges of less than 20 yards, 50 grains is hard to see unless you are a very consistent shooter.
Some woods, Sitka Spruce in particular, don't vary much within a given spine range; maybe 50 grains total. POC will vary 100 grains or so and Douglas Fir can vary over 150 grains. DF is still my favorite arrow wood, it just takes more shafts to match up a close dozen.