So how EXACTLY do YOU find a satisfactory load? Not your loading procedure but how do you establish a load is good? How many rounds do you shoot until you say this is a solid load?
Without getting too deep into weeds and typing a novel. I don't set out with the goal of "the best I can get." For example, I'm not going to do all this testing like people do and then try to pick out the lowest SD or best group. Because I know that it's a very good chance what you pick won't be the best. It just appeared to be the best at the time.
So, I will instead define the worst I'm willing to accept. Let's say I decide I want at worst a 7sd. I'll run sims and such with 3 and 5 shot strings and see about where the cutoff is for somewhere around 80-90% chance I'll be at my minimum SD. Then when I shoot my 3 or 5 shot strings over chrono, I can eliminate the combinations that miss that mark.
What this does, is it ensures that I didn't eliminate a load because it happened to not shoot well in my small sample size. Which tons of people do, and they don't know it. Because they never go back and test the "bad" loads.
After that's done, I'll have X amount of samples that passed my minimum threshold. Since you have to pick a place to start, I'll normally start with the sample that produced the smallest numbers. As I said, you have to pick a place to start, so I just start there. I load a more significant size, 10-30 rounds, depending. If at any point, the SD goes over the threshold I set above in the initial testing, I stop and move to the next.
Once I finish, I'll have only a handful or less charge weights that made it to the "finish" line, and I'll have a fairly significant amount of sample size. I'll have the first 3-5 shots I used initially. And then I'll have the other 10-30 shots. So, I'll normally have a minimum of 15rnds of a charge weight in a handful of charge weights that were acceptable via the limits I set above. I can then decide which to use based on that data.
I do a similar test for seating depth and such.
Sounds like a lot, but it's not that much more than most people use with their 3-5 shot strings. I just move to my stage two with many more charge weights to test, and I use larger shot strings in phase 2.
The main difference is, I'm not looking for the "best" because the odds of finding the best with low sample sizes is not good. I'm looking for "at least this good" and hopefully I get better. But at worst, I'll get minimally acceptable.
As I've said earlier, when you have guys like Cortina or F Class John, they stick with a single cartridge for years at a time. So their loads they are currently using are products of much, much larger sample sizes. They just post the low shot string samples in their videos. If you were to give them a brand new, never used cartridge, they very likely wouldn't find the "best" within the first barrel or three. They would however, progressively work their way into amazing ammo as they always do.
That part is always left out of people's consideration when they reference these guys. People think they can take their 22-250, do a little bit of testing, and find ammo combinations that shoot as good as Cortina's 7mm XYZ (whatever he's been shooting for a while at the time).