I finally tried the 3-stick method on the 4th Mix. It worked for one section, but in the other 4 tries, the sticks kept shifting around and my wrist was aching.

Cymbal works fine, though.
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Extra Rush up to Level 9!
Surprise! Extra/Encores for GF8/DM7 are the new Special Extra/Encore stages
If you forgot, She said... leads to Infinite, and Mikeneko Rock leads to Model DD3.
Beating Model DD3 on DM unlocks Stop Spinning Me in Circles BSC (21).
Beating Model DD3 on GF unlocks new notecharts for Classic Party 3 on BASS EXT (52), and all new OPEN (56, 65,

98)
Beating Infinite on DM unlocks Carnival Day BSC (21).
Beating Infinite on GF unlocks all new notecharts for Fireball on OPEN (difficulties still unknown) and I guess BASS EXT as well.