This is wrong. If I want to handle a problem by researching it, I have a goal in mind ("solve problem X"), and I'll look for things that will help with it.
Interview preparation specifically avoids that approach. Instead, you're supposed to become familiar with every possible problem, in case it comes up during the interview. Most of them, obviously, won't, and from a "research" perspective that means that nearly 100% of the time you spent in preparation was wasted.
One more thing is that, research takes time. Companies want ability to cut short this time which is required from inception to delivery of a product. They prefer a candidate who already has prepared linear algebra, if you are going to work on deep learning at the company.
This is wrong. If I want to handle a problem by researching it, I have a goal in mind ("solve problem X"), and I'll look for things that will help with it.
Interview preparation specifically avoids that approach. Instead, you're supposed to become familiar with every possible problem, in case it comes up during the interview. Most of them, obviously, won't, and from a "research" perspective that means that nearly 100% of the time you spent in preparation was wasted.