Creating Consistent Courses in Rise 360

I'm looking for tips on creating consistent look and feel in courses built in Rise360. Our design team wants us to use our color palette, fonts, and imagery. I've looked at themes and it seems we could do some customization, but when I make changes and save, it only applies to the current course? 

Would it be better to design one theme and save it, then just duplicate it each time? Are there any other efficient ways to do this? Editing each theme and block is really painful.