Modern calibers can easily be fired 5-7 times between trimmings, maybe more. It's not even something I think about anymore. Here's why:
Let's say you buy good brass that costs $1.25/each (or $62.50/50 which is ballpark for Peterson brass now).
If you shoot that case 5 shots and toss it, that's $0.25 per shot. If you shoot that case 8 shots, that's less than $0.16 per shot.
If you buy a $75 trimmer (which in all honesty isn't a bad price, though I get by fine with the cheaper Lee Case Length gauges for when I do trim) you might now get twice the brass life but you're getting it with brass that likely already has the primer pockets loosened up a bit, and likely needs to be annealed (more $$ and time) and at some point you have to ask what your time is worth.
Buy all the annealing and trimming and cleaning tools you can find, and the best you'll do is to make your ammo component costs drop from $0.25 per shot from brass down to, absolute best case, $0.08 to $0.12 per shot. That doesn't even begin to consider that most guys will load hot enough to loosen their primer pockets before they get to 10 firings, or that if you're resizing aggressively between shots so as to maximize clearances and reliability (some people do 0.002" shoulder bump, some people fully resize, some people find some happy medium) you'll likely be working the body of the case enough that head separation becomes a possibility after several shots.
So you'll end up with hundreds of dollars worth of gadgets and hundreds of dollars worth of time, if you value time at all, to make your brass last a little longer but in doing so you end up shooting lesser quality brass as it's just 'more worn out' by the time it gets to the end of tis life. The most you'll ever save in this process is $0.25 per shot and $0.15 per shot is a more realistic estimate.
