I've had at least two doctors during my time in the states.
I had the family doctor, which was probably due to the range of the insurance coverage, and the CF specialist, who was at a Childrens Hospital, and may had some parts that were within the range of the insurance.
I believe I was at Childrens til I was 21, because I remember being old enough to drive myself a few times, and when I was doing PFT's the machine was actually TOO SMALL for me!
I was referred to a CF clinic for adults--a new concept back then--and I still had my family doctor, who knew about CF. Fortunately, the two hospitals where the CF and family doc were at happened to merge, so I was essentially seeing two docs at the same hospital. They were both pretty good, and my family doc seemed more strict than the CF doc did...the family doc even chewed me out when I dehydrated after practicing my karate in 95 degree weather!
Of course now, there is no such thing as a CF specialist in Japan, or if there is I'd probably have to go to Tokyo for an appointment.