When I used to sit in with the Baltimore (Maryland, USA) Ceili Band, back in the 80s and early 90s, the band would play a medley of tunes for almost every dance except waltzes (for waltzes, a medley of instrumental waltz tunes were sometimes played, but a single song in 3/4 time was also sometimes used, particularly if a good singer was present.) Even for dances that had a signature tune (e.g. The High Cauled Cap, The Stack of Barley), different tunes would be used after initial playing of the signature tune (sometimes the signature tune would be brought back at the end of the dance.) The one exception I can think of was The Sweets of May, where the signature tune was played for the entire dance.

Don