I have a few 24 fret necked basses also. Agreed that a standard repertoire doesn't require more than 20 frets but I deliberately invent passages at the end/heal of any neck I own. I do the same with my Ex-Factor neck creating something that takes advantage of the lower A. (strung BEAD) It may be an accent or feature within a bass-line/structure but my aim is to incorporate it musically into a song or solo piece where it adds expressive emphasis. It works especially well doubling a guitarists' brief lead fills between changes.
This '60s 15 fret Dano could probably suffice in 98% of bass needs
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