I think it depends on your career goals and it depends on the specialty.
Let's say your goal is a higher salary and/or a better work schedule, the more specialized your skills the more likely you are to be able to command that, given that your chosen specialty is very much in demand and there's not a lot of therapist specializing in that specific field. For this specific goal it's good to analyze the specialty using a supply and demand lens.
The first scenario is where supply of PTs outweighs the demand for the service. Let's take the common ortho path. A lot of PTs work in ortho and even if you specialize in manual therapy and achieve FAAOMPT, chances are it'll be very hard to differentiate yourself because of the sheer volume of PTs who have this kind of specialty. And in the eye of the patient, whether a PT has achieved FAAOMPT might not be that relevant to them. In such case, looking at it purely from a higher salary and/or better work schedule lens, this kind of specialty might not yield the results you're looking to achieve.
Now let's take a second scenario where the supply equals demand. If you specialize in vestibular, the demand for this kind of service will likely remain stable over time because the number of patients suffering from vestibular conditions is unlikely to drastically change year over year. So if you specialize in vestibular, you will have a skill that will attract some more patients, but it's unlikely to yield a critical volume of patients to power your whole practice.
The last scenario is a specialty where the demand from patients outweighs the supply of PTs. A decade ago, this would have been women's pelvic health. In the recent years, it's now men's pelvic health. It's a hugely underserved population with over 50% of men who will suffer from at least one type pelvic health issue (pain, ED, LUTS) in their lifetime. Hospital networks like Kaiser Permanente and Select Medical have caught onto this demand and are heavily investing to start male pelvic health programs at their facility to answer the demand from patients. Multiple clinic owners are also seeing this imbalance in supply and demand in this specialty and are looking to hire PTs who have this kind of skill. If you're interested in getting started in this specialty, there are free resources here:
Pelvic Floor Courses - Free Resources — IPC - Integrated Pelvic Care. So people who have this skill can spearhead programs at their hospital, can open specialized clinics, etc.
That said, not everything is about finances and career growth. If you're looking at it from a intellectual curiosity perspective and helping patients, then all specialties are worth diving in and taking a look at. At the end of the day, it depends on what you like! As PTs we do amazing work and we have so many important specialties that are crucial for helping our patients.
