The accordion is not usually a favorite instrument of mine but there is a man here in town (Dale Wygant) who does amazing things with it.
I remember one time he was accompanying an International Folk Dance recital. At one point he said, This next piece is Hungarian- and it has 11 beats to the measure. I counted, and sure enough I thought I counted more than 10 beats.
Then he said, OK, this next piece is Bulgarian and it has 13 beats to the measure. But no problem; I'll just add 2 beats.
I gave up!Ebbie