[quote name='paul_c2' timestamp='1329588350' post='1544660']
But that doesn't fit, because you don't need frets to create some higher notes, just know where the harmonics are. My 4 string, 20 fret Jazz copy can achieve 5 octaves, for example, the same as my 24 fret fretless.
[/quote]
Well, I think it does fit because a 21 fret 4-string neck does cover three octaves in the normal and straightforward sense. Although I'll accept that a range of harmonics (and bends) are also available.