I did Pathoma throughout the school year. I had 2 days between one exam and the pathology shelf to study for it. I only reviewed the first few general pathology chapters and skimmed a few other sections I felt weak on (ex. heme/onc, reproductive, etc). I didn't review the systems we had just completed (lung and neuro).
If you have 3 days to study for it, I think you can definitely get through a good chunk of Pathoma. I would focus in the general path (fairly high yield) and the sections you feel weak on. It was a tough exam, but I felt like if you've been keeping up with path throughout the year (ie. not cramming the night before exams), you could reason your way through most of the questions even if you hadn't reviewed that particular topic. If you can get through all of Pathoma, or even the stuff you feel weak on, I think you can set yourself up for getting 80+ percentile (IMHO -- of course, this also depends on your test taking abilities, such as ruling out wrong answers, being able to pick up on buzzwords, etc).
Hope that helps.
