Interviews are (with varying degrees of efficacy) meant to gauge fundamentals - so I think you're presenting a bit of a false dichotomy.

That said I haven't really solicited advice on either. My concern is more specifically related to how to frame my past employment and medical issues for a future employer - not so much making it through a technical screening.

I was, and am, curious about what others deem important to their career and craft (e.g. fundamentals), but like I said it's mainly curiosity. If you have something to share I'm all ears, and if not I wish you well.

The context of the original poster's question makes it obvious that they are looking for help interviewing. I'm not disputing the importance of learning "actual fundamentals" and for those, I agree that CTCI isn't the right choice, but it's a very popular book for interviewees for a reason.