Yes, my fourth grader still leaves out letters and reverses S and 5. I'm not worried, because he reads well, understands math, has a wonderful imagination, loves art and music, and is an athlete. And if he's like me, while he is copying the words, his brain has 350 other thoughts going on at the same time. That can be a bit distracting.
For instance, while doing this page, he was thinking about how amazing swamps are,with trees and plants that grow IN the water, and how the people must have dealt with the insects. He wondered about malaria, about body paint as a skin protectant, and where they grew their veggies. He wondered if the water is muddy or clear, and what shade of blue or brown or even yellow it might be. Just for starters. So he was a bit distracted. I harp on him to stay on task, but really I love his curiosity. I love that he wants to learn.