I used to trim pistol brass and would today if I were loading match grade ammunition. I only use new brass. I spot check them for length and to see if the mouth is square with the side of the case. If all appears OK, I chamfer and load.
For top accuracy, I do it all - cut primer pockets to uniform depth, deburr the flash hole, trim all to same length, carefully chamfer and outside deburr---- and all that other stuff. For almost all of my shooting, I just load and shoot. I can't shoot well enough to tell the difference.