volunteerbee,
I have read of these steps being done one at a time to see whether they did or didn't enhance accuracy. Seems like the writers concluded that individually they didn't amount to squat, most of the time, but together they helped. I will say that with reloading, consistency is a key factor. That goes from brass prep, to powder charges, to bullet seating depths. I think alot of our accuracy improving operation were adopted from the BenchRest community and if it helps them shoot bug-holes, it has to help the rest of us.
I do de-burr the flash hole on all my brass. This only has to be done once and the theory is that it aids in perfect ignition, everytime (consistency). I do clean my primer pockets each time I prep my brass. I don't like that crude on my casings, not sure that it hurts anything, just a personal peve. There are alot of other steps that are used but you have to settle on what works for you and develop a consistent routine. JohnnyK.