Best Way to Reuse Course Assets

Over the years, we have developed a large amount of courses and now have an inventory of screens, nav/menu selections, graphic elements, KCs, variables/triggers etc. Each of the inventory groupings, e.g., Menu, Graphics, etc are scenes within a "working course." When a new course begins, we would copy a scene from the "working course"into the new course,let's say we are designing graphics,  use what we need, delete that scene from the new course and import the KC scene when we do the KCs etc. Is there a better way of reusing your assets? Closing out, saving, re-opening etc takes too long.