I think you may be getting a little too deep in this.
I do a lot of weight segregation because I assemble 100 case lots from once-fired brass. The objective is to ensure consistant case volumes across the lot. My criteria is +/- 1%. 30-06 cases tend to weigh around 185 grains or so, depending on manufacturer so, if 185 is my "average", a lot will vary in weight from 183 to 187 grains. That's a fairly tight range but I have 5-600 cases at a time I'm working with so it's easy to assemble lots that close.
All cases are resized to SAAMI minimums, trimmed to the same length, flash holes deburred prior to weighing.
You start with the heaviest case because, theoretically, all else being equal, that's the one with the least capacity and will develope the highest pressure. I say theoretically because it works that way pretty much but the fact is that if you are really going to that extreme, it;'s best to actually measure the capacity of each case in water.
I do all this because I'm trying to beat guys shooting cast bullets from stock military rifles where the 5-shot record is something like 0.15", but the average is closer to 1".
That said, in standard chambered rifles shooting commercial bullets from just about any manufacturer, I'd buy 100 cases, load and shoot them without a single thought to all the crap I go through normally because the volumetric differences within a single lot of 30-06 cases from a know manufacturer will not vary enough to cause any pressure and/or accuracy issues for what you are doing, out to at least 300 yards, IMO.