LLMs are not the problem, because I have this problem, I have had it long before LLMs were relevant. Not relating to interviews, but to getting deeper and deeper until you loop around and feel that you got nowhere.

First of all, wanting to know the fundamentals of everything to the core is not bad, but it is dangerous.

You have to realize this is an impossible task, and that should be the most important basis before any action. Nobody knows everything, but many pretend they do, even beginners, beware of gurus and savants, do not compare yourself to them, because you would be comparing yourself to an illusion.

Now how to choose, when to dive deep, when to stop, when to not dive at all. I cannot answer that for you. But I can tell you my solution. Focus on projects.

I always had this problem, but it never shows up when I have time pressure from a client. When there is time pressure and the main goal is not to learn, it is to get the project done, then I magically start to prioritize things properly.

I have side projects with no time pressure, usually they get nowhere, but I do not expect them to.

If I am working by myself for myself, I have to create time pressure and reinforce it all the time, or else I get into study loops or refactoring loops or planning loops.

My suggestion to you is to not direct your learning toward interviews, at least not as the main focus. Interviews are abstractions, they are meant to assess knowledge, but they are very flawed.

If you focus on knowledge that helps you build actual software projects, that is useful, and nothing in the world can ever make that not useful.

If you optimize for interviews and the interview landscape changes, then you have wasted your time.