One time I was having problems with my 45 ACP not chambering all the way. It was driving me nuts trying to figure out why. So for lack of a gauge I disassembled the pistol and used the chamber in the barrel. It finally turned out to be a crimp problem but this simple solution helped me find it. But to answer your question I agree with the othre guys mix it up as long as case lengths are the same.
"If there must be trouble, let it be in my day, that my child may have peace." - Thomas Paine
Vietnam Vet 1968 MCB 53 Danang
for plinking it don't matter to me ,but it can make a differance in target shooting.
fed brass is thicker than most so the same charge in fed brass will fill case a little more than say win brass thus increasing pressure a tad .
For competition I only use Fed or Winchester brass, for all other whatever I have, except the new Speer with the small primer.
I do not sort the brass as to how many times it has been fired, I don't load anywhere near max so I don't worry about it.
All brass gets a good inspection after tumbling.
Most people are like slinkies....not much use but good for a smile when ya push em' down the stairs.