For me, I can't remember so many numbers, so using notation makes it more convenient for me. Also, there are some cells where I can't immediately determine which number to fill in, and I have to reason through them one by one to get the answer.
Thank you for your comment! I appreciate the support. Killer Sudoku can be challenging, but with practice, I'm sure you can master it too. Keep enjoying Sudoku and challenge yourself to beat your personal best. Good luck and have fun!
