My wife used DIT when studying for Step 1 and as she often likes to remind me, she did do a little better than me. Just to clarify, I do not think that DIT is a bad product. In my opinion, it can be easy for this to be the case with Doctors in Training (DIT). I have seen far too many students end up with suboptimal scores as a result of following the majority and not determining what works best for them.
One-size-fits-all approaches to studying for the USMLE (or any test in medical school for that matter) are tricky because everyone learns differently.