Take load development as far you want but I look at this subject differently theses days.
There's so much to consider in working up a load that it can get ridiculously overwhelming and time consuming, not to mention every round you shoot is wearing the barrel out. Story coming...Way back when I worked up a fantastic load for my first long range rifle, a 6.5-284. Two memorable things happened, I shot high score by a large margin at our local annual 1000Y match and the other was it took 300+ rounds to find that load using 3 different powders, 3 brands of primers and 2 brands of bullets. The barrel only lasted 1200 rounds including a set back at 900 rounds and taking many hours to do it all. Lesson learned, LOL don't be like the old me. The win was cool but knowing what I know now there's a good chance I could have won anyway in as little as 30 rounds of load work instead of 300 rounds. Besides that, it was who guessed the wind the best that day, not the most accurate load on the line, that determined the high score.
Since I'm not a benchrest shooter I don't need to attempt sub 1" groups at 600Y. 3 inch at that distance is fine for me off a bipod.
Greatly simplifying the process of load work is when I ran across the ladder testing method.
I pick a good match bullet with high BC that is not jump sensitive. One powder that is as appropriate to the case as possible and that is not temp sensitive, and a good primer for the case. This all vs my old way as described above.
I don't put ultimate trust in getting the lowest extreme spreads because the best ES might not be centered in a node. If it is then that's wonderful but as the barrel wears, components run out and replaced, temps change, the ES you once had is compromised. Furthermore I'm not sure I can even shoot inside the best ES.
I don't care "to a point" how accurate my 100Y groups will be, I know if in the node they'll be good enough. Though through trial and error what shoots best at 100Y doesn't necessarily mean that will happen at distance all the time. I care how well the groups will be at distance and I'm looking for how tight the vertical is.
I did an experiment once with OCW and with Dan involved on a post concerning the subject. I did a ladder test at 400Y and a OCW at 100Y. I found the high node to be right on for both methods but the low node didn't coincide with what he estimated it would be so I decided to stay with the ladder method because I have easy access to long range spots all over the place where I live and most of the time the nodes are more obvious. If I have doubt I run two ladders, which happened recently. Nothing against OCW but I chose ladder, a node is a node and if "confirmed" each method is fine.
Here's my strangest ladder test out of many that I've done. I'd show you some of my others done over the years that came out normal but photobucket has them in jail. Usually in a ladder test the shots will rise and stop at the low node then rise again and stop on the high node. I have my own 6x47l reamer used for the last 7 barrels so I knew approximately where the nodes would be with this bullet, powder and primer combo. Low node wasn't so obvious on this test but as you can see the rifle is very accurate at 323Y. So at the high node, which rose higher, the vertical and horizontal tightened up. I picked shot 12 as my powder charge. It's hard to see but shots 11,12 and 13 are a tiny group. BTW this ladder test was in .1 grain increments, not .2 or .5 grain like normally done.
Load found in 13 shots, I didn't bother with a seating depth test, why would I. This load shoots very good at distance often touching splats, has reasonably low SD at 6-7, and shoots well at 100Y though it could be better. The group I was most proud of was 4 shots at 900Y into 3" with maybe 1" of vertical. I have a few very similar to that at other distances. I blame me for misses because it's for sure not the rifle's fault do to inaccuracy.
The high shot was the one sighter. The other was from a friend that wanted to shoot my rifle, though I hoped he'd shoot at his own target instead of mine, lol. I didn't even see it till I got home and took a good look.
BTW, I started doing what I call running the barrel in before I start load work. I run the barrel in by shooting steel for at least 100 rounds(fun, right?!) with a lighter charge and by then the velocity will have picked up 100 fps or so.