Mike....
I believe the "super cleaning" mode is left over from prior x900 manuals. If you note, the follow on text of maintenance mode functions makes no mention of it.
There is also no "super clean" in the maintenance program. There is an initial ink load function, which is similar to what one does on initial setup. Unfortunately, it requires doing one entire bank of carts at a time.
I used it when I had a total PK/MK dropout, which was, I suspect, caused by air introduced by changing black inks.
Recently, after a few weeks vacation, I had some VM problems...clog or air, most likely. Test, clean, print, repeat, repeat, repeat....two days worth....about ready to give up....3rd day, magically worked on first test...
Similar clog on 3880, after a few month idle....two cycles and done.
John