If a dance for a set number of couples has its 'own tune' I feel cheated if when I'm in the leading couple the band have changed to a different tune. So much so that I've just bought a CD by the American band Childgrove, so that I can call Fandango to its own tune all 3 times (all the club recordings have a change of tune, and a band who sometimes plays at our club refuses to to play the same tune all through the 3x64 bars).
The music can give clues about what to do. Dancing Blaydon Races to a second tune instinct can take over and I'll start to Promenade after the swing, never with the right tune.
But some 'sets' sound good together. And going back to the first tune gives a hint that the dance may end soon.