No 'die contact plus XX turn' makes a precise cartridge, there is too much variation in dies, shell holders, presses and cases themselves for any such "instruction" to do more than get us in the right ball park; individual die tweaking must follow. Using Redding's "competition" shell holders work by taking care of excessive shoulder setback without thought but it's nothing we can't do ourselves with small die adjustments.
We ONLY need to make our ammo fit a 'cartridge gage' IF we want our ammo to fit into any rifle ever made for that cartridge, same as factory ammo does. But, a major part of reloading is we can make our ammo actually fit OUR rifle with some precision. To do that we need to size to make the resized shoulder lengths match the fired case shoulder lengths. Doing that requires that we measure off the case itself, not just dropping them into a steel 'go-no go' case/cartridge gage.
As 1858 says, brass cases are insufficently identical in their springback to size with better than approximately 2-4 thou spread at the shoulder.
