Kia ora Jen,
I think as they are all separate activities, you'll need to run all of them separately.
Possible workarounds:
are all the courses in one category? That's a filter option you can select when you run the feedback report.
put all the course in one category then see above (should be allow to select multiple courses really, feel free to raise a suggestion thingy)
send yourself scheduled reports for each course then you could mosh them all together in Excel.
could be other ways that I'm not aware of
Going forward you could use Lee's idea of setting up a new Feedback activity on the front page which you can then share across several pages.
And archiving all the old feedback activities.
I've never set one up so if you do decide to go down that route I'd be interested in how it goes for you.
Ngā mihi,
Larry