Overall, not very. I would say of the 3 I would focus on ophtho b/c knowing some of those key words and phrases can get you points (ie. copper wiring, vision loss "like a curtain coming down", and esp. which things have pain and which are painless). IMHO, the majority of ENT questions are pretty straight-forward whereas, for me studying ortho just wasn't worth it for the handful of questions (probably only 5 or so questions, not including peds stuff like hip dysplasia and SCFE)...it requires too much knowledge of anatomy that I don't remember (like bones and ligaments in the foot for example). All that being said, if you do practice questions (I recommend USMLEWorld) you will most likely run across an example of any question from these sections that you would see on the exam. So to sum up, do practice questions and that should be sufficient and if you are really short on time, skip the ENT and ortho and focus on ophtho.
