Sheiks dash dance is anything BUT uselss...
You perfrom it different though.
With pretty much every character dash dancing is pressing left-right, if you do that with Sheik though her dash dance is really short and most of the time you don't dash dance but turn around slowly >_>
So instead of regular dash dancing you should dash, stop, dash, stop.
That way you extend the lenght of her dash dance with pretty much no lag, its easier and makes her dash dance something worth using.
This is probably abit unclear so I might make a vid explaining what I mean later.