It's been a lot of years since I've played for serious dances like the Lancers, but it's absolutely crucial to the flow of the dance that different time signatures and tempi are used. Even the Virginia Reel employs different tunes for this reason.

My wife's grandfather has been dead for 50 years and played fiddle for dances circa 1914. The sounboard of his fiddle still has the dance bracket tunes/songs roughly scratched into the surface. It's a long time since I've seen it but they always seemed like tune lists for the Pride of Erin and Canadian Two Step.

My impression is that there has long been a tradition of playing tunes in sets for dances in Australia.

Regards, John