.unless you only do batches of once shot, twice shot, etc.,
That is in fact what I do but on larger lots then 20 . I won't even work up a load with different brass unless I have at least 110 pieces and most of the time I have 200+ of the same head stamp .
Why 110 ? I generally load in 50rd batches and I like to be able to have at least 100rds of any one particular load . Anything under that and it will not give me a whole days shooting . The extra ten pieces is just to be able to replace damaged or lost pieces .
So I'll have a bag of lets say 250 pieces and I'll just keep loading from that lot as needed untill they are used up while keeping all the spent cases in another bag . When that lot as been used I then prep all at once and start over .
I have a 400+ lot of 308 LC-14 I'm going through now and a 600+ lot of 5.56 LC-14 I'm going through . I also have a few other 250+ct lots of other head stamps and calibers . I use a lot of LC cases and tend to allocate specific loads to specific year head stamps .
I keep them all in Ziplock bags with a note inside describing head stamp , times fired , times annealed , and some have bushing size used and case head space length . There are a couple firearm specific lots as well .