Firstly i’m gonna state that I cram for exams and ive a good technical background and also I wouldn’t recommend this study strategy to anyone unless you know it works for you but….
I started from scratch on May 1st and studied full-time for the month. I did the same for L1 and L2 and it worked for those as well. I used Schweser for each and dipped into CFAI now and again for more complex areas. For L3 i did the eoc questions in both schweser and cfai but in L1and L2 i did just Schweser.
Its by no means a nice month though but getting them outta the way in 18 months with 12 weeks study is defo nice!
To conclude, if you have a history of being able to cramfor exams, then its definitely possible.