I did not do DIT but knew some friends who did. I agree that it may be helpful but takes up a lot of time to do and basically is just "teaching" First Aid. It is good for "completeness" so you don't miss any little areas (psych, biostats, epidemiology, genetics, etc). I used Pathoma and loved it. Definitely recommend it - pathology is a huge part of the test. Don't neglect the small areas if you want to do really well on the test, but focus on path.