Functionality is simultaneous. All sliders are always emitting CV from their individual jack sockets; all sliders can simultaneously be emitting MIDI.
Worth pointing out: the whole thing is written in Teensyduino. You are free to customise/modify/hack this object as much as you want; initial functionality is very much a suggestion. So if you don’t want to map some sliders, either set your code to ignore them, or just don’t map them in the DAW.