I only seperate a few hundred pieces of brass by head stamp for testing new loads to keep everthing the same. I use the round robin method and then after that it is prety much any brass regardless of head stamp. Though I am not competition shooting either.
I like using H-335 with 55 grain bullets, and Varget, or RL-15 for the heavier bullets. I will end up testing a few other powders just for the heck of it eventualy.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.