My first genres (supergenre1) are extremely broad, so I might cut those out eventually. We'll see!
Using brackets, I can exclude levels that are non-existant, so that makes it quite versatile too.
%supergenre1%\%supergenre2%\[%supergenre3%\]%genre%\%artist%
I can have a simpler system for some kinds of music where I know fewer genres (I don't know electronica that well) and then have a more complex system for those who have more genres or where my knowledge is more extensive such as for prog rock and metal.