btcapital

If you have a finance background already, you’re probably going to be overkill for level 1 if you’re starting now. Of course everyone is different and you know where you’re at better than anyone else, but that is A LOT of time and you might forget some of the concepts you’re studying now by exam day.
To answer the question, I passed all 3 levels using almost exclusively only schweser (I used some of the CFAI books for level 3).