With VV 133 powder you may want to go with a little more as it loves neck tension.
I'd shoot 3-shot groups at .003", .004", .005" several times using your standard load and see what you get. If you can't see a clear difference, I'd use .003" and don't worry about it. Worry about reading your flags instead. Good luck!
You bring up something else I was wondering about. If I use more, (or less), neck tension, do I need to adjust my load with powder charge weight or bullet seating depth to make it work?
Maybe. But the only you'll know is to step away from the keyboard and head to the range. Good luck.
I started out in the IBS but quickly got bored with a heavy dose of 100 & 200 yds. Glad I started there as I quickly learn how much I did not know but was around some excellent shooters. I moved to groundhog shoots out to 500 yds and was told the 6ppc would not shoot that far. Ha Ha, I showed them how wrong they where. So the bulk of my ppc history is perhaps a bit different than most. .004 has been the answer for me in most cases. Less never worked for me. I have used .005 on a couple barrels but .004 is the go to. .262 necks, .258 bushing.