In addition to what other have said, which is good advice, I also drop the slide on the same few cartridges multiple times. Measure them before and after, this will help reveal a functional set back scenario.
I've also performed a bench test by pressing the nose against a bathroom scale, then compare what it takes to create set to that of recommended neck tension spec., what ever that is, I can't remember off the top of my head.
I will first find my functional OAL/COAL by performing the plunk test and by determining what will fit the magazine and feed reliably from the magazine. Once I've determined the functional OAL I then work my charge up at that OAL. And any time I change bullets, and, or the oal, I perform the same process again.
9mm is already a high pressure cartridge to start, so it is very pressure sensitive to set back, pressures can spike very high depending on the amount of set back. IMO .010" set back can have a noticeable effect on pressures depending on the powder and charge, but it's certainly needs to be addressed. .020" can cause a significant amount of pressure spike and is certainly a reason for heightened concern and correction.
Just one country girls perspective.
Barrelgal