It's one less variable removed if you get the same lot.
From Vietnam (Hathcock) to today, the working crew wants same lot.
When I competed, I got as big a lot as I could afford. Most long term competitors who dont reload, generally by same case lots.
Others have seen mixed lots make no difference with some newer factory ammo.
My old habits die hard, I will keep buying in quantity same lot, makes a difference in long range, jmho.