I just shot my 1st 3-Gun match on Saturday. Specifically, I shot at the "Choate Multigun Melee" at the Mountain Valley Sportsman's Ass'n outside of Hot Springs, Arkansas. I'm sure I could name a dozen things that I learned, but I'll just hit the top few, seeing as how this thread is "Name one thing that you learned at your last match.
1) A $600 Mini-14 with cheap, substandard magazines is capable of a malfunction.
2) So is a $2,000 AR using quality mags.
3) High-capacity mags count. Reloading takes longer than I thought, even in a semi-auto.
4) It's good to achieve all of your goals, especially when they are: (a) don't shoot anyone; (b) don't get shot; (c) arrive home with vision and hearing intact.