Mixing .223 stamps to me depends on what stamps we're mixing.
Commercial and military? No thanks, unless it's a very moderate/mild load. And the only commercial cases I keep in rotation are Winchester, which are actually due for retirement soon (neck splits).
Mixed recent vintage LC stamps (and a handful of WCC)? Ok for out to 300 yards. 25.0gr of Varget, a CCI-BR4 or Remington 7 1/2 and a 69gr Nosler will shoot cleans on the 300 yard target in mixed years LC cases out of an AR service rifle.
Max-throttle 600-yd .223 loads? Sorted headstamps, track the firings. When these are retired, they're good for scrap.
With my .30-30, I don't mix headstamps but I never reload more than 2 boxes (40 rds) in a sitting anyway, and haven't fired 20 in a sitting since it was new.
Handguns? Sort headstamps? Yeah, right. Shoot 'em, gather 'em up, clean 'em, reload, repeat. The only exception is with Magnums, and those get tracked in boxes of 50 anyway. Everything else gets loaded bulk into big buckets.