I dunno about this. In radiology, there is a ramp up in efficiency for 3-6 months when entering private practice, but if you go from fellowship to academics, it's pretty seamless. At the end of my fellowship, my attendings told me to just start finalizing unless I had questions. I know a lot of surgical specialists go straight from fellowship to attending pretty easily. I think it's pretty weird that pathologists would require 2-5 post-fellowship years to become "real" attendings.