This still seems off. If you wanted a deep understanding, you'd go for academic books about algorithms and data structures, then go try the leetcode problems without the coaching advice. Otherwise we're just coaching towards the particular interview format, which is only proving you can learn to game that particular format. Coaching for an interview format doesn't solve real world problems which is why people are annoyed about these interviews.
If its helpful, I did read one of those academic books (Segewick) thoroughly. But personally I found the practice questions laborious. You have to do the setup, you don't get the feedback. You don't know if its going to be easy or hard. And it takes some effort to see similar solutions. Conversely, once I paired with it with leetcode, I could e.g. finish reading about topological sort and then go look up common problems. I found alternative solutions, comparisons, got instant feedback, etc. To me, the combination of a quality DS&A book with leetcode for the raw (targeted) practice is a really great combination.
