Terrible advice - reading Harrison's alone would take the guts of 6 months, plus Harrison's isn't geared towards the USMLE. This is really perplexing advice.
Stick with UWorld and MTB. I used FA for sections that I felt deficient in. Used Kaplan here and there. If you want to be really adventurous, you can supplement with UptoDate.
This is what I did for a 256 but, as with all advice, you can take or leave it - just pick what works best for you. As I mentioned, there's no silver bullet.
EDIT: Furthermore, you do not need 6 months to study for this exam.