Although 24 frets is not typical, both the NYC shop and Japan build 24 fret versions. In particular, Bass San Diego seems to have decided that they like the JJ 24 fret 5's, and they have been maintaining a few in their inventory. Nice looking basses. I like the black one.
Regarding the utility of 24 fret basses, that of course, depends on the gig. Most cover gigs don't require the additional range. I like it because I still haven't let go of the concept that I might find a gig playing Real Book tunes again down the road; and I use that part of the scale for some of the heads. So, the NYC order I just placed is for a 24 fret instrument. But, in truth, those gigs seem to be much less in demand. And, one can usually get away with playing those parts down an octave. So, I see 24 frets as "nice to have" vs "need to have." YMMV
For me it was that I needed an ash/maple NYC and it was available. I dont use the highest frets on the gig. I just judge the overall bass and this one is awesome.

, It took some serious cleaning to get off the leftover human. The frets were beaten to heck, and somewhere down the line a pickup cover was added and removed- leaving only the holes in a well worn PG. Peter from Sadowsky sent me the new PG and it was a perfect fit. We had discussed sending the bass to them for the fret job, but we both felt that based on shipping charges it was a better idea for me to have it done locally.. Fred at The Repair Zone did an awesome fret job and now she feels and looks "newish". I love it! Crappy cell pic of course...