I don't bother to sort or count the number of reloads on my 9mm brass. (or trim it) If the pocket get loose, the case splits, or it has poor neck tension I toss it.
The mixed brass shoots as good as I can. (which may not be saying much
)
As an example of 5 rounds with mixed brass.
RMR 147 RN 3.5 Bullseye OAL 1.135 S+B SP
933.00
940.00
935.00
933.00
943.00
Average 936.80
ES 10.00
SD 4.49
PF 137.71
Mixed brass and the ES and SD look pretty good on this load.
In general with charges as thrown by my Lee Pro Disk, not checking each one,
using mixed brass I would estimate an overall average using different powders at around 25 for the ES and 12 for SD.