That upper register is mainly useful for playing Jazz heads and solo parts. Also, I use that portion of the fingerboard to cover some keyboard parts for ensembles lacking an actual keyboard.
But, standard cover fare rarely needs anything more than 20 fret positions for the recorded bass parts; simply because that’s what’s the studio had.
My current variety cover gig has a guitarist and horn player; who both seem to feel that solos are their sovereign territory, and the bass player should just stick to the recorded part. My Blues Brothers Trib gig is much more free wheeling, with solo spots all around.
The answer about available scale “need” depends pretty strongly on the individual gig. I’d rather have more available on a given gig and not need it than too little; though that can also be a very interesting musical “challenge.” I also prefer to gig as little scale capability as needed.
The various bass guitar configs all have their advantages and limitations. For pop cover work, I currently favor the Will Lee 4 string config, with 22 frets and the Drop D Extender. I can cover almost everything with that. For small ensemble standard Jazz charts, I do like being able to take heads in the upper register. Charts, like the Take 5 head, require a high F#, requiring either 24 frets, E - C on a 5 string, or the 6 string instrument.
No single answer; depends on the parts required / appropriate for a given gig.