Hardest or easiest is not a good evaluation for NBME.
I saw posts sayin "is form 5 the easiest?"
What can be easy for you can be super hard for me.
I took NBME 5 not long ago and I'd say it had lots of stuff that I not necesserely like, but anyway NBME is the most accurate predictor.
Ambition is a dream with a V8 engine. EP