Number of frets is probably less important than the accessibility of the frets high up in the register. It takes a fairly large hand to get around the heel of a Les Paul or the neck/body joint of a Strat for frets above 18 or so. Many newer body styles have deeper cut-aways and contoured neck/body joints that make accessing the upper registers much easier.

The other consideration is sound. The neck pickup has a very different sound when it sits under what would be the 24th fret as opposed to under what would be the 26th fret.