Craig--I am not sure that you are right when you talk about the original fake books--By definition, fake sheets, fake books, handwritten chord charts, etc, really de-evolved from more elaborate scores--it makes more sense to assume that, through a process of gradually reduction, the score was reduced to a melody line with chords and lyrics, then symply to chords and lyrics, then, to either lyrics(for the vocalist) or just chords, and finally, simply to verbal and non-verbal cues that alluded to the chord progression.

My guitar teacher taught me to work from charts, but in practice, especially when we were working as pick-up musicians backing a soloist, he taught me a whole series of cues that referred to the info that would have been on the fake sheets, if we had them.

I do know that there really aren't practical limit in the size of a the band that can work from a fake sheet, because I have seen bands with 18 and more players work from a simple chord chart--the trick being that, within the horn sections, each player knows which part of the chord to play, and the leader gives cues on where they should be and when--