If we get caught without a vest we get DQ'd. If we take a pic of the fish with no vest, the fish doesn't count and we get DQ'd. Can't always see your vest when camera is pointed at the fish on a Ketch board, but we've had some geniuses lay their vest in the kayak and take a pic of their fish with the vest in the background.
If we're putting on or taking off rain gear and have to remove the vest, we have to go to the bank. If someone sees you not doing that you get DQ'd.
I have an NRS I wear during cooler months and an auto inflate during warmer months. Mine will either auto inflate, pull a cord and inflate or a mouth tube to manually inflate. Our season opener is in March each year and I replace my cartridge each year before the first tournament.
My gym has an indoor pool and before I change out the cartridge I jump in and test the old one. May or may not help but gives me the warm and fuzzies. I will periodically jump in and go limp with my NRS just to see how it orientates me.
I don't worry as much about flipping, etc and being conscious as long as I have my vest on, which it's always on even when not in a tournament - it's if you black out, hit your head or go unconscious for whatever reason. You may float face down and drown, but at least you have a 50/50 chance with a vest on.
One other thing a lot of people don't think about is the rule of 120. If the water temp and air temp combined aren't at least 120*, it can be dangerous. If I'm in a kayak and it doesn't hit 120, I wear a wetsuit. The only issue is if you have to pee, you pretty much have to go ashore. If push come to shove I'd rather sit in a puddle of urine than die though.