I think we'll have to agree that there are 'bands' and 'bands'. Many of the bands I've played in have been almost 'scratch' bands, often enough with folk I've never met before. The variety repertoire had, at that time a certain number of 'standards', but many would be 'winged', without rehearsal, as everyone knew them from having heard 'em at least once. (Not always, though; with the 'Tropicana' band, playing Creole stuff, I just followed the Caribbean percussionists with a samba or beguine, and everyone danced just the same...).