It would be useful to create a macro (a sequence of commands) and attach it to a shortcut. Here are a few examples I can think of (which would be useful to me):
Move every 4th note in a selection down an octave (that is, move a note down an octave and advance four notes)
Accent every other note (add an accent to a note and advance to two notes after that)
Store a named motif (a note pattern) in a macro so it can be inserted any time, anywhere (the clipboard can only store one thing at a time, but I could setup several motifs to insert in my music)
Call up the Insert Measure dialog to insert a user-specified number of measures at the current location, paste the current selection into them and put a double bar at the end
I'm sure I (and other users) could easily come up with other examples. Also it would be nice if the Repeat key could be used to repeat the last shortcut, not just the last note entered.