For maximum accuracy you want everything the same every time. If you only neck size, your brass grows a tiny bit every firing (and possibly not uniformly between pieces of brass), eventually needing to be FL sized. You can get very good accuracy doing this. To get the best accuracy though IMO, you want to just barely FL size every time giving every piece of brass (hopefully) uniform size.
I mostly neck size my brass for tactical and varmint guns, FL for hunting rifles, and do minimum FL for 6ppc.
