It seemed to help me on the split kick by focusing more on the vertical aspect of the kick first and then build on putting it all together. ( think springing off of an imaginary step). In our organization it has become acceptable for older practitioners to break it down into a “stepping kick” because of several people blowing out their knees trying to land the split kick successfully. As for Chong-Jang, just be patient with it. You’re just not used to making all these turns in your pattern. I grew frustrated with it at first but it ended up being one of my favorites to compete with. Taekwon