Say I have 10 tracks all with a side chain volume shaper (cableguy’s shaperbox, for example). At the moment, I can only figure out how to use a single midi track to send to 5 of those side chain tracks (the 4 midi send + the midi out). Is it possible to somehow “send” the midi track to other midi tracks, all with their own midi sends, so that I don’t have to duplicate the same midi data to all the other midi tracks?
Not within Cubase proper - the 4 sends is pretty much the limit.
However if you get a third party virtual MIDI cable then you can route your MIDI Track to it. Then any VSTi can use the virtual cable as its MIDI In. I use LoopBe & have had it forever, quite likely there are better choices nowadays so take a look. Virtual MIDI cables are useful to have around to solve routing limitations and problems.