There are some interview processes that are unfair, pedantic, or irrelevant to be sure (manhole covers come to mind), but most of the questions are at least founded in basic CS knowledge.
A good analogy is the math section of the SAT: some people can take the SAT naturally and understand the question models it follows on the first try. Others will go to tutors and memorize how to solve them, essentially programming themselves for different word questions. Which group do you think will have a more enjoyable and valuable experience at a difficult college that requires a high SAT score?
It seems (to me) that it would be better to acquire the actual skills so you can improve yourself and do the job rather than memorizing problems and solutions. Even if you believe your job doesn't involve CS directly (webdev, for instance), a more holistic understanding of computer science is sure to benefit you in understand how and why the APIs and frameworks you use were designed, and how you can write clean and performant code.
If your problem is performing in front of engineers on a whiteboard, and not the theory, then you don't need to practice questions, you need to do mock interviews.