Shots per charge before you trust a ladder's speed trend?

[2labs]

I keep seeing ladders with one shot per charge where the speed goes up and down as the charge goes up, so I built a made-up ladder to see how much of that is just normal shot-to-shot variation.

6.5 Creedmoor, 24 inch barrel, 140 gr ELD-M, H4350, CBTO 2.230, six charges in 0.3 gr steps (38.5 to 40.0 gr), 3 shots each, 100 yards. The numbers are made up but realistic. It is not a load recommendation, check your own manual.

The average speed climbs about 8 fps per step. The shot-to-shot SD inside a single charge is about 10 fps. So one step up is smaller than the variation within one charge.

I ran it through Loadscope, the program I make for Mac and Windows, so I'm biased. It scores velocity flat spot (5%), velocity SD (20%), mean radius (40%) and vertical dispersion (35%), and it picked 38.8 gr. It also said that at 3 shots a charge, 38.8 and 39.4 are too close to call, and suggested 10 rounds each to settle it. The Results screen is in the picture.

How many shots per charge do you shoot before you believe the speed trend? Do you add shots, or make the steps bigger?

Wrote up how many rounds a ladder needs here: https://loadscope.app/learn/how-many-sh ... harge.html