I'll agree with
@CK1.0 on this topic.
I have tried many different methods over the last 32 years that I have been handloading and have come to the conclusion that I have wasted a lot of components and gas trying to find the "Best Load".
To start off with, I'll measure the distance at which the bullet is up against the lands and reduce that by .055" to start for my seating depth. If there is pressure test data for the cartridge I am using, I will look where the min and max are and load up quarter or half grain steps between those two points usually in samples of three cartridges each. I'll shoot these at 100 yards while recording velocity. This is all assuming we are shooting a cartridge that uses around 30-40 grains of powder.
If the barrel is meant for PRS use, I will pick a load on the slower end that both grouped well and had velocity numbers that were not wild. I'll shoot that for the first 200 rounds or so until it looks like the velocity has stabilized. Then I will retest using nearly the same method but choosing the velocity window I am looking for. I'll load these in .25 grain steps and samples of three and again pick the best two or three groups with good velocity SD/ES numbers. I'll take those two or three loads to my long distance range and shoot them in groups of 10 at 700 and pick the best performer.
When I started loading my most recent barrel chambered in 25GT I knew I wanted to use N150 powder. Had I not been comparing 135 hybrids and 134 ELD's I would have had a start load determined in 20 rounds fired, 5 of which were to season the bore and get a rough zero. After 75 rounds of practice drills over a couple days I used it at a one day regional which put another 110 rounds through the bore. I retested powder weights again between 2590fps and what I figured would be about 70 fps faster and tested those five samples (15 rounds) where three samples shot well and I retested those at 700. So, 60 test rounds altogether of actual "Load Development" were used.
Never touched the seating depth. Will it win a bench rest match? No, probably not. Will it hold under half moa at distance more often than not and bring PRS trophies home? Yes!