How much curriculum in your degree will you actually use in IB?

Most of the introductory accounting and finance courses are helpful as they give you a base knowledge of financial concepts and accounting principles. When it comes to the higher level courses, what you get out of them is very much dependent on the professor. As you mentioned learning material simply for the sake of passing an exam is a giant waste of time. In my experience most of the professors that rely on tests are the academics who have very little real world experience and teach based on a text book, which is a complete joke and useless. When I was in school and signing up for classes I would always check which professor was teaching the course and jump on LinkedIn to see what kind of real world experience they had if any, and if they had spent most of their career in academia I wouldn't take the course or would see if another professor was teaching it. I've found that the best professors are adjunct professors as they are typically individuals that have decades of real world experience and teach on the side while working their full time job or retired. I was able to get quite a lot out of school by doing this as most of the adjunct professors relied on projects instead of tests because they understood that real hands on experience was a far more effective educational tool.