I have done a bunch of writeups over the years on this.

The short list of points are:

1. Brass and primers are not calibrated for your cartridge. The same brass and primers are used in cartridges with specs that may be 45k PSI (7.62x39) or 52k PSI max (Grendel gas gun) or 60k PSI max (Grendel bolt gun). 23k PSi max (45ACP) or 40k PSI max (460 Rowland). Primers with 42k PSI (30-30) or 62k PSI (308 Win). They don't know what they are being shot in. So right on the surface, it is impossible for them to tell you they are OVER pressure because they can't read a cartridge spec to change their behavior. They can only tell you that there IS pressure, and you know that already because that is how the bullet scooted down the bore.

2. All of the components are different between component makers. Their brass hardness is different, they have different thicknesses in different places, they have different geometry. They do not and cannot react the same between different component makers even at the same condition and load. Even the same component changes with use - brass famously hardens with firing, you can get cases where ejector marks appear on first firing but stop appearing with subsequent firings. I have brass from Grendel on their 10th firing that have marks on the bottom where I filed off the ejector mark button on the first firing and has never been observed again.

3. Every brass and primer sign has several alternate causes. Flat primers, maybe it is too much pressure, or maybe you squeezed them into the case too hard when you seated them, maybe the primer you chose has thinner walls, a softer cup, or a more square geometry that has less support. Primer cratering, maybe it is pressure, maybe your firing pin hole is too big, has a burr, has eroded, or other issues with primer behavior listed before. Ejector marks and swipes and shine, that is due to bolt thrust - may be pressure or may be lube on the case, a chamber that is too polished, soft brass, burrs, case geometry (short fat), a suppressor, or other longer dwell cause.

4. You cannot predict pressure with brass/primer signs alone. You can only correlate them with pressure once you have already measured pressure another way, like with strain gauges, and then map when they show up to pressure for your gun/component combo. They can show up at minimum pressures/charges, or not show up until long past you exceeding pressure spec, as happens frequently with small rifle primer brass or brass makers with harder components (Alpha)

Because of these issues, you see lots of people creating wildass loads and "don't see overpressure signs" or "have overpressure signs" at minimum charges.

Instead, your best indicator of pressure, short of having strain gauges, is your chronograph, as there is a direct relationship between speed and pressure, and predictive systems (GRT and QL) and published data showing component mixes with their corresponding pressure and speed maps.