Wow...so many varied responses: Everything from "I never check" to "I check every round" and everything in between. Interesting.
I get it that my progressive press may not catch all defective brass, which led to the question. Since it was bugging me, I decided to go through about 2,200 9mm loads and case gauge every single one, just for piece of mind. It took about 2 hours or so, but afterwards I found several questionable rounds. 3 of them had a significant bulge at the base, although closer inspection didn't reveal any visible cracks. Several others just sat slightly higher in the gauge than others, so I set them aside as well. After pulling the bullets, reusing the primers and recapturing the powder, I just tossed all questionable brass away.l.p.
I'm not really certain as to what kind of issues those rounds would have had upon firing, but I definitely feel better knowing they're gone. At the very least, the bulged brass would have caused jams.
Anyway, thanks to everyone who responded. From this point onward, I will likely check all finished rounds, just to know that I've been thorough. Doesn't seem to take much time...but I definitely see a Shockbottle in my future.