For me, the answer is clear. I struggle with a low half-court ball, where I attempt to spin an approach shot. I miss a lot of these. Now, I will say that when I practice, I can hit this shot quite well, but in a match, when I tense up, I start decelerating and very frequently make a mess of it. It is an ongoing problem that I'm trying to fix.
I find it difficult to practice match situations. It is one thing to hit the ball when you know where the machine or your opponent is playing them, but in a match situation, transitioning from serve into hitting the half-court +1 can be tricky, and that is difficult to practice with a machine. The modern ones with tracker might help, or you simply have the machine on long intervals, hit a shadow serve and then hit the ball from the machine.