Getting centered in a seating node will shrink groups by half or more. If everything else is "right" with your set up and bench manners it will shape up those weird looking groups and can pull those "one outs" in within reason. If you run in increments of .003" you will eventually roll into the nodes, if you run bigger increments there's a chance you'll skip over nodes. The bigger the increment the better the chance you are skipping over them.
I agree you can tune powder very close but to get the absolute most accuracy out of any combination seating depth must be tested. There is a remote possibility you could pick the majic base to ogive measurement tune it with powder and be at the absolute most accurate seating depth but you will never know for sure without thouroghly testing it.
On the subject of nodes how wide of node do we really need? Aren't we looking for the most accurate node so we can find the center or sweet spot of that node where group size can be cut in half again.
I measured .014" of throat erosion in 1400+ rounds on a 6.5x47 Lapua Improved barrel recently. The barrel was still shoog very well even though I didn't do a very good job of keeping up with it. A barrel will favor the "position" of the bullet in the barrel. We are using the distance to the lands as a reference to locate that position in the barrel. Once this position is found many barrels, actually IMO most barrels will still shoot as accurately in spite of throat erosion to a great extent. Maybe not quite as accurate but still "in the node" accurate.
So while a node that's .002 or .003 wide may seem narrow in regards to throat erosion it stays constant by it's position in the chamber as it relates to barrel time I believe.
I've checked distance to the lands many times and found my throat had eroded but the gun was still maintaining the accuracy because of the position in the chamber not the distance to the lands.
Find the node in .003s fine tune it in .001s to find the sweet spot of the node. Keep shooting it in that position regardless of distance to the lands until accuracy degrades. If / when accuracy degrades check distance to the lands and adjust accordingly.
What distance should I do? 1,2 or 300?
If it’s windy when I get there then I will disregard 300.
Also, I crimp only those going into a semi-auto (for me thats 300BO, 223, 243, 6.5cm, 308).
I do it for reliable live round extraction in the field, not for SD.
Don't see an improvement in FPS SD.