I just got my shelf score back today (took two weeks) and scored a 75 (for reference my Step 1 is a 233). I read Blueprints twice during the rotation (once over the first month then again in the last six weeks), went through all of the UWorld Qs on OB/GYN (204) and reviewed them again, and did 14 of the APGO quizzes. I used OB/GYN Recall during the rotation for pimping questions and it was helpful despite having incorrect information (eg. ovaries receive blood primarily from the ovarian arteries off the aorta or renal artery, not primarily from anastomoses with uterine arteries as the book states).
I recommend doing all of the APGO quizzes, and also trying to really intentionally learn from your experiences rather than do the work and study on your off-hours. Seems obvious, but I think if I'd been more invested during the rotation and really aggressively learned about each topic, the final would've gone down smoother. Everyone I took it with (and everyone I asked) needed the entire time and felt terrible about it upon finishing (but it was my first shelf exam, 2nd rotation), so don't be surprised if you have a similar experience. Good luck to everyone taking it, I used this thread and hope my post was useful. The test itself seemed to address more tertiary level information, as in they're not going to test whether you know that metronidazole is the treatment for BV, but that you know that topical will have the same efficacy as oral, or they won't test you on identifying DVT in a gravid patient, but on knowing what the best confirmatory test is. There were three breast cancer questions on mine also, along with at least three urinary incontinence questions, so I thought Blueprints (despite having some typos itself and my view that textbooks are an overall inefficient modality for learning) reflected how the exam weighted material nicely.