Not necessarily. I think it was good in having someone go through each section and highlight what was actually important to know, how it would likely be asked on Step 1, etc. For example, I had no idea how to study biochem using First Aid, and it was helpful for me to have someone take me through the section and give me the highlights, typical presentations, etc. They'll stress it's not important to know every single enzyme and intermediate, but to know the heavily regulated ones and anyone that if altered would cause a physical disease state with a clinical presentation. There's only so much time and capacity you have to learn certain things, so it's nice to not waste your time on concepts that aren't likely to be tested.
Like DIT, I also think HY is better done on your second pass of First Aid as they do go fast. Also, like DIT, they probably more often than not will just go through things like Tables/Drugs fairly quickly. Even on specific facts though, they will point out things not to learn or spend too much time on. For instance, hem/onc drugs. Don't spend anytime trying to memorize which drugs are given for which types of cancer, etc. This is listed in First Aid, yet it's mainly irrelevant. Outside of a few which may target CNS tumors, Step 1 will never ask you a question framed about knowing specific chemotherapy drug regimens for most cancers (minus if a drug, aka rituximab, is targeted against a specific protein marker that defines a particular cancer...i.e. B cell lymphoma). They're much more likely to ask you about drug mechanisms, side effects, etc. In other words, it's incredibly low yield to waste your time on memorizing that etoposide is used for testicular carcinoma or that vincristine/vinblastine can be used for Wilm's tumor.
I haven't seen much of DIT, but it seemed to long for me when considering getting it. And, way way overpriced. HY is only $200 or so with an AMA subscription right now and I feel like it's been helpful enough for the sections I was having trouble with.