[rahimnathwani]

This may (may!) be true for something like math concepts that build on one another.

But in OP's example, much of the CFA and CAIA is about man-made concepts, taxes and government regulations. What does 'understanding' even mean in this context? If you 'understood' what rule XYZ means about the fiduciary duty of a financial advisor, does that mean you'll always remember it, or be able to derive it from first principles, even 20 years in future?

[Jensson]

You learn what the structure of tax logic look like so you know what kinds of regulations to expect and look for. It isn't like rules doesn't change in 20 years, but the way those rules are structured probably didn't change much.

So basically before learning you have to look up the entire logic, after learning it is like looking up a table and go through each point.