I spoke from my limited point of view as an artillery officer, so I have never really worked with more than one or two Army physicians at a time. I'll agree that the EFMB is unnecessary for physicians. The physicians and PAs in my units have usually done the EFMB, but I'll acknowledge that I don't know that many Army doctors and their EFMB status.
However, if it were me, and I had 68Ws working for me, I would challenge myself to do it. Especially now that ACUs don't have branch insignia, an officer is an officer, and as the Army draws down, differentiating yourself from your peers matters. Any time your rating chain includes line officers, little things like that may or may not help, but they certainly don't hurt. My brigade commander (I'm in an operational unit) loves PT, so his priorities are my priorities.
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@WernickeDO said, other military schools can open up opportunities. The minimum score for the course may be "the standard," but if there is a waiting list, a unit will usually send those with the best PT scores.