Testing is good. But sometimes theoretical considerations help clear the fog. The energy comes from the powder. Different quantities of powder are probably the most significant variable, but there are other considerations with smokeless powder -- the deterrent coating, the size -- length, thickness, hole through center, etc. of the individual granules, and probably others I've forgotten or don't know about.
I get a kick out of people who can weigh to a single granule of powder. Do you use a big one, or a small one to get the weight just perfect? In the thread on mixing lots of powder, Larry Costa -- a truly world-class shooter -- remarked that N-133 had all different sizes of granules. I don't know how the deterrent coating is put on. Likely there can be variance there, too.
You can sift ball powder, but not stick powder. IIRC, in an old thread on BR Central when it was a list, the most consistent velocities were obtained by sifting ball powder, 748 for the PPC. I don't remember the actual chronograph numbers, but ES/SD was way down there. Whether or not it gave the smallest groups is another story.
Offsetting this, with one lot of Rel-22, I managed single-digit ES and an SD of 7 fps in a large case -- a .300 Dakota. Charges were weighted, but I never tried simply throwing them. Different lot of R-22, different results.
Dave Tooley use to use an old Bruno center-fill measure for 1,000 yard BR, and he was pretty successful -- Dave ranks 16th on the IBS lifetime Long Range Marksman list, and with all his commitments, doesn't make as many matches as most of us. I do believe he's changed to weighing his charges, but knowing Dave, he might just have said that to get the rest of us off his back.
So the "offsetting" gets us back to testing. There are too many variables to say one tool always works best. A chronograph used to test a large enough sample size will let you know what works best for you.
Then we have column B. Most of us, at one time or another, whether it be for short or long range, have used powders that gave lower ES/SD with velocity, but didn't give as small groups/highest scores as another powder.
So it isn't just the chronograph, but the target. And there are so many things that affect "the target." In the final analysis, world-class shooters have used quite an array of tooling. The one thing they obviously have in common is they've figured out how to use their tools.