Like others have said, NFAA 40 CM target shooting is very tough. I, too, have been shooting 300 rounds this winter. It took me a lot of shooting, focusing on form errors to go from 230's to 250's. Some days, I just don't shoot well and the harder I try to correct whatever form errors are causing errant shots, the worse it gets. As Dave said, I try to focus on making a good shot, trusting the process and not the results. As Kegan also pointed out, I now know when I make a strong, good form shot, whether the arrow impacts exactly where I was aiming of not. Conversely, I also now know when I make a less than quality shot, even if the arrow impacts exactly where I was aiming. Sometimes it frustrates me more to see my arrow impact where I was aiming when I know I didn't make a good form shot.
All of this said, some archers just enjoy shooting at tennis balls, chasing nocks, etc. That's fine too. It's all about what brings out the joy of archery to each individual archer. Your comment, Forest, about the only shot that counts is the first one is certainly true in the hunting realm. In the target archery world, the mindset is that the most important shot is the arrow you're shooting, each and every one of them.
IMO, shooting spots develops strong form which translates to good hunting accuracy. The benefits of muscle memory translate to improved hunting accuracy. I recently shot with a very renowned, world class archer. When he shoots, he holds the bow back for a long time, probably six to ten seconds on each and every shot while shooting spots. He is also a very accomplished hunter. When he hunts, his shots on game animals are much quicker than the way he shoots targets. He relies on muscle memory to help him execute a strong, accurate hunting shot, essentially doing everything he does while shooting spot targets-Just doing it quicker on game.