I have studied algorithms in college. I believe the goals of leetcode vs the goals of graph theory may be against each other.

A good graph theory course abstracts away the details of code and pursues the goal of understanding how many problems can be expressed concisely and clearly through graphs.

A good leetcode practice ... honestly just hones how patient you are in debugging and memorising various code patterns.

If you want to pursue money, it's almost always better to pursue leetcode exclusively