Well there's the what do you want to be your area of focus and what actually is. I have certificates in Gerontology and Homeopathy, and did a lot of gyn modeling. I have a rural practice and see whatever walks through the door. Unless you're in an area with several other NDs, you're not going to be able to focus on one area and keep your doors open. I do a lot of general check-ups, including gyn exams. Lately, I've been seeing an influx of patients with bipolar disorder.
I have not done homeopathy as much as I would like. My older patients are boomers and not really anyone older, which is a little disappointing for me. I have been seeing a decent amount of women with gynecological concerns, so I'm glad I am very comfortable doing pelvic exams.

On a side note, for those of you interested in gynecology, malpractice companies charge you an increased rate, even if you're only doing routine paps!
It's nice to have a focus when learning, but in actual practice you must be flexible. Try to focus on something with a broad application that's not to "woowoo" for the general population. Remember- you can always take CE courses to work on weak areas.