Case trimming is something that I have largely avoided. I keep my brass segregated and set up the crimp, usually a Lee factory crimp die, for each "batch" of ammo. That might be 50 or 100 rounds, but the brass is the same head stamp and has always stayed together.

I'm thinking about loading it all and dumping it in ammo cans. But I'm thinking I'll need to at least trim it all once. I have it in my head that the case length, and crimp, are more important than keeping brass segregated???

I've got a Forster trimmer and an old Lyman trimmer, but there has to be a better way? This would be primarily for 38/357, 44 spl/mag, 45 Colt, and 45 ACP. I can continue to prep rifle brass with the Lyman trimmer.

What's the best way to trim a bunch of pistol brass fast? Or am I overthinking this and I shouldn't worry so much?

I use the LEE piloted mandrels. You can trim cases while watching tv if you want. Now you can chuck them in your drill and make things easier. Pretty foolproof with the pilot and it's built in stop.
I hit them with the de-burring tool while in the holder, and sometimes with a rag with Brasso if I want them to really shine or to take of the signs of being in a cartridge holder a bit too long.

If you have a plethora to do, or have excessively long cases, you will probably get some sore fingers with the little cutter but now they make on with a big wood knob. much nicer.

Just one way.

454C and 500L. I keep them annealed and trimmed. Case prep is tedious.

SO, I use a 5C collet with stop in my lathe so the case is positioned relative to the base. Lock the carriage, put a tray between the spindle and carriage so that when the collet is opened the finished case drops into the tray. Put case in collet with right hand (making sure it is against the stop), close collet with left hand, run cross slide in and back out. Open collet and repeat.

Use similar method of cleaning primer pockets - chuck Sinclair carbide tool in lathe, leave lathe running with tray in same location, press case against tool until it stops cutting, drop in tray. Repeat.

Trimmed every batch when new and kept them together. I asked the same question and everyone pretty much said I was too OC about it so I stopped. I don't know if I see any accuracy difference but I definitely feel the difference when crimping. I've been slowly getting all my batches trimmed again simply because I like uniformity. I don't worry about my ACP cases since I taper crimp them and I've yet to have one grow to where it wouldn't fully chamber.