It is so hard Marion and way beyond my knowledge - even if we just looked at Ireland, we will find that the Donegal style is different to the Claire style... There seem to be limits but I guess that much is down to feeling and listening to players you enjoy although if you were playing for dancers, I would suspect that you would have to adopt certain standards.I have been dabbling with the dance music for years and still don't really understand it - I just know how I feel it - maybe one day, my hands will become good enough to put what I feel into practice.
Jon