Poll: Leetcode or DS&A To Beat Technical Interviews

I'm bad at timed tests. Really bad. I've never passed one Hacker Rank test, and have taken 5-7. On half of those, things "click" right when the timer ends and the pressure is off. Nothing I can do about that. The other half though, I never pass the optimal solution test cases, but can at least understand the question enough to brute force my way through. I have enough data engineering experience at this point that I'm getting interest for dedicated software engineering positions(ml focus) rather than just the typical, all-encompassing-but-likely-to-be-an-analyst data science roles. There is an obvious knowledge gap, as any engineering-heavy role will test on DS&A, and the only CS class I took in undergrad was problem solving. So, how should I direct my focus to prepare? I could do nothing but practice problems, and then go over the theory that I see pop up frequently in solutions. I could do an entire audit of a DS&A course and then practice with Leetcode after. Or, I could start with the topics that are most commonly tested, study the theory, do practice problems, and then repeat for the next topic.