No big deal to mix pistol brass for practice or plinking loads. I don't keep track of the number of times loaded with them, just toss them if the necks split when sizing. I do separate revolver cases because the necks get worked and some of them are pretty hot loads. I separate my rifle brass carefully by lot and headstamp. I put all info possible into my loading notes - something might come into question down the road. I also number each batch and write the batch on the cartridge box. If it's a test batch, I can note that number on the targets and not get things confused when I get home, measure targets, and add the data to the notes.