Split should have been one disc for MM and SS, and one disc split between KZK and "the rest."
SS has surprisingly few tracks. SS itself is practically a best of itself. KZK gets a whole one track which is pretty wack. I get that the songs don't lend well to a Best Of format, but you can swap out Stem for Kuki, throw in Okonomide, or Doppleganger. Ringo no Uta low-key is not one of her best songs. (And Stem is a snooze.) No ZCS tracks or B-sides apart from Suberidai is a sham.
The picks on disc 2 aren't terrible. For what it's worth, they're the songs that come to mind when I think post-KZK Shiina.
"Jihad is the soul of EMF"--Lena