I load 5 different charges .2 or .3 gr difference, shoot those to find the node I want, then pick 3 different charges (the node one above and one below) shoot those for group. Once I find the load I want then I chronograph the MV and move on. I have found the further you shoot the easier it is to see things on paper 400-500 yards. If it all goes right I am done in 20 rounds.
I load up ten rounds, starting with book minimum, increasing .2g at a time until book max or ten rounds. I will chrony each one and look for a flat spot in velocity. If I am able to reach book max without pressure signs, I may go up another .2 or .4g to find the max, but only if my velocities are slower than what I want in the first ten rounds. Then move on to seating depth if needed. Usually the groups are good enough and I move on.
I have about 800-1000 rounds through my stock 6.5 creedmoor barrel. I’m not concerned with shooting all ~3500 rounds through it and replacing it. This test will still leave me with another ~2500 rounds out of it.
Ladder tests are shot with one round only, per powder charge. 300 yards can be done, but 500 yards makes for easy to read results. For .223 case, I step in .2 gr increments, for all other short actions, step in .3 gr incrememnts, for long actions step in .4 gr increments. There can be a low node, and a high node. We want them going as fast as possible, so most test the charges in the high node. When there are three charges that group together, then go load those for groups, and shoot 5 if the barrel contour is heavy enough for 5 consecutive shots. More times than not, the charge in the middle of the node is the sweet spot. Roll with it.
If you HAVE to keep tinkering, you can play with seating depth variations, but all other factors should be identical; brass, primer, powder lot and charge, and bullet.
What length are you guys loading your cases to for ladder testing? Are you going with book length and then play with longer seating depth?
Or do you load to lands and play with shorter seating depths for safety sake?
I like to shoot three rounds at each charge weight in my ladder test. That way I'm not relying on one perfect round at each weight to base all my future loads on.
Grab one of the hornady gauges so you can see the length to the lands and then back it off a bit from there, at least that's where I start.