It's an art. Same as music, poetry or any other endeavor. It takes tonnages of failure experiences to become good at it.

It's like someone who wants to learn how to play the piano. They might learn music theory or read about it and when they actually sit at the piano and try to play....they suck. That's because in this world, nothing gets good without practice and tonns of practice.

For TA, the practice is in real live money losing/winning applications. My rate is about 88% and that's after 15+ years of practicing.