Don't grind, bind to your mind.
One of the most common mistakes people make in preparation for technical interviews is grinding Leetcode. Mindless grinding serves no purpose. You must make an intentional effort at learning with the goal of true understanding.
There are various techniques to this but here is one to get you started.
First, set aside time for study and practice. For example, you could decide to Leetcode for an hour every Monday, Wednesday, and Friday. This amount of time could be enough if you already have a strong foundation, but you can adjust up or down depending on your experience level.
After setting a schedule, write down the topics you are strong and weak in. If you've already taken a data structures and algorithms class, you should have a good idea. Two common topics that people are weak in are recursion or dynamic programming.
Let's say you are weak in recursion. On Leetcode's problem page, set the tag to "recursion". Then sort by difficulty. Pick out around 5-10 problems to work on. For example I have picked out 9 problems, divided into 3 difficulties: