If it's any help at all, when I play Dance I always focus totally on the centre circle - because you can see any changes to the left or right hand ones in your peripheral vision and react as necessary.
I keep the left thumb on Button A and the right thumb on Button C and just press the middle button B when necessary...
It seems to work for me, because as long as I concentrate on that centre circle, I can usually win the game...
As for Shape, I think the more you play, the more you learn the sequence of the shapes - and then you know when to press buttons quickly to scroll thru to match the falling shape or you know you have plenty of time because it is just one or two changes to make to match the Shape. That takes off some of the pressure (and stress) so you don't make too many mistakes