Funny this should come up as I just posted something about this in another thread.
When starting out I use a load chart from several locations as a guide. I will choose my powder and fill to the shoulder of the case and then weigh the charge. This charge weight will be close to the most accurate load 80% of the time. This is due to most powders are the most efficient when case fill is at 90% or better. I compare this to the load charts. So as an example, the load range for a case is 38-42gr on a chart. My case fill test to the shoulder weighs in at 41.3gr, which is within the margin of safety as its on the chart. From that measurement I will take plus or minus 1% of the charge weight and build 3 test loads of 5 shots each. So my ladder will be 39.9, 41.3, 41.7. 95% of the time this will produce an accurate load, I might fine tune a couple 10ths of a grain from one of those and may end up with a load that is over book max. So say my 41.7 gives the best accuracy, I will take that load +/- .2 gr to see what is best. Obviously book max could be lower, say 41gr in the above example, and loading to my suspected best load might be a little sketchy. At that point I do take a little more care, and build up a little slower, but unless we are seeing really heavy compression with the 41.7 load, Id still load 5 and if I dont see wicked pressure signs on the 1st round of the string would shoot all 5. This is obviously a simplified example, as smaller cases like 223 give alot less margin and require smaller jumps than something like a 30-06.
I still ladder my loads out, I just take a shortcut to figure out where I need to start. I only use this load for trying to find max velocity and accuracy at the same time. For loads where Im trying to build something a little milder, Ill start in the middle of the load range, take .5gr jumps. Say the load range is 38-43. Ill start at 40gr, work down to 39 and up to 41, with 39, 39.5, 40, 40.5, 41. Ill take the best group and +/- .2 gr and see whats the best to fine tune.
For pistol loads I dont use this technique.
or how it is settled(compressed) what kind of powder shape etc.
