I'm not familiar with the recordings you mentioned, but then I am in England and have more interest in English music. I got the story off David Oliver of Folkworks and he's been playing for dancing for many years. He knew many of the old Northumbrian musicians and Jimmy Shand often played for dances in Northumberland in the 30's and 40's. I did notice on some of the old recordings on the Farne website, that the old Northumbrian musicians were playing two tunes two or three times through, even on recordings made live at dances.
As to decoration it's a matter of taste . I prefer moderation, though I confess my fingers are not quick enough a lot of the time :-) I still think it is too often overdone.
As to the previous poster, I can imagine playing "Old Joe Clark" or anything else for 30 minutes is likely to leave a little fed up of the particular tune.