When you spend a lot of your dollars in an exam with ~43% pass rate, you need to grab all the low hanging fruits first. Put in other words, apply the Pareto principle and find the smallest possible subject area with greatest weightage in the exam; which is CFA level 1 in our case.
Let's look at the weightage for all the 10 subjects or topics for CFA level 1:
It's clear that Ethics is the most important standalone topic. Other topics have dependency amongst themselves and are also heavy conceptually. Also, if you had to pick out the companion to Ethics, it's obvious that 'Quantitative Methods' would be your best bet. As, Quants or Maths is also a standalone topic and easy to cover in less time. Obviously, this won't be true for a lot of people!
If we combine 'Quantitative Methods' & 'Ethical and Professional Standards' we get a weightage of 23-32% or in other words Maths & Ethics covers almost 1/3rd of the CFA level 1 curriculum.
If I was a Level 1 aspirant, I would first try to get a grip on these topics!
