Brass must be batched.
When using a new batch I first trim them all to the same length then weigh each one and discard any obviously different ones.
Even if it is the same manufacturer, if a new batch differs much from the previous batch, consider re-working up the load. As a minimum check the zero and grouping haven't altered.
I also weigh all the bullets and reject any odd ones.
First firing is done with a start load and used for practice/rough zeroing etc. Even if you FL size, the cases are never sized as tight as new. Trim again after the first firing, then just check periodically. A safe load in a fired case might be overpressure in a new case, or at least shoot differently.
Batch process with a single stage press is the way for consistency.
When charging cases, start with empty ones loose in a tub, then put the filled cases one by one into a loading block. The plastic insert from .44mag pistol ammo is just right for .308 sized cases.
If you use a powder thrower its still best to throw a low weight then trickle up to the final value in the scales, rather than blindly trusting it.
If using a digital scale check its tare and drift regularly. Buy a calibration weight too. I tare the scale with the powder pan/funnel, then make a note of the weight of the pan on the bottom.
Every time I remove the pan and fill a case I check that the scale shows the exact negative weight of the pan. This gives good confidence that the scale hasn't drifted or otherwise gone wrong. When the batteries are low the readings can be erratic, a nearby mobile 'phone can interfere, etc.
I use the marked pan as a test weight too. If it varies from one session to the next I check the scale carefully and re-calibrate.
Only filled cases are ever present in the load block. Only loose cases from the tub are ever charged with powder. Avoid distraction e.g. answering the 'phone, making a cup of tea, going to the loo partway through the batch.
If you first weigh the brass and bullets, then check the completed rounds afterwards, you
should see very good consistency, enough to detect a badly thrown charge. For weighing brass and bullets a digital scale is most efficient. Buy one with a sensible range and resolution to cope with the weight of your completed rounds. DO NOT think of using it as a powder scale too, that requires a much much finer resolution.
I've seen digital scales advertised as powder scales that are completely unsuitable. E.g. ones which resolve to 0.2 grains. This means your loads could vary by 0.4 grains, even if they were perfectly accurate (they aren't). Milligram resolution scales are readily available and perfect for the job.
Very important to check the completed weight when loading pistol calibres, where e.g. a double or empty charge from a turret press is quite possible. I've seen gallery rifles with blocked barrels where a squib load has lodged a bullet in the barrel and another one (or more) have been subsequently fired. Easily done in rapid fire competitions.
If all this sounds too complicated, really it isn't, and you will KNOW that your rounds are correct.