I have always thought that I have to do just one thing at the time. But it turned out that it is much more efficient not to split the work. Now I often see reports from international teams that abandoned the separation of UX and UI and have become more efficient.
After I stopped stressing out about choosing between my favorite directions (creatively, professionally), my life has definitely become calmer. My work is more interesting now, and, in general, I get results faster.