Vote for a "Graded" list.
Like the existing "To Do" list, a "Graded" list would work the same way.
The vision: Currently there are two lists on the right side that instructors usually see: "To Do" and "Coming Up." This would add a third list that would look and work just like the "To Do." The only difference is that the "Graded" list would be placed below the "Coming Up" list, and on it you'd see the *last five* items / links that were previously on the "To Do" list but have been moved to the "Graded" list because they were all graded. To see all items on the Graded list, you'd click text that says, "x more..." just like we currently do on the "To Do" list (or alternatively you'd see a little arrow like those that expand and contract a module). By default, the list is short, just five items. But one could expand to all items, or reduce back to the default 5, with one click.
The reason this is a good idea is that it uses the existing format and navigation methods in Canvas and would provide fantastic convenience for instructors to return the Speedgrader. There could be no quicker method.
Need: The need for a Graded list is the same as the need for the "To Do" list: quick access to SpeedGrader. Items in the "To Do" list disappear as soon as one has graded all of the items for an assignment. In order to return to the SpeedGrader for an assignment -- to re-grade, to review in response to student questions, etc. -- one must click many times, e.g. click on Grades, scrolling, click on dropdown window. Items are hard to find in Grades. The "Graded" list would show the graded assignments. Just like with the "To Do" list, click on one to open SpeedGrader. This would be the fastest way to get back to SpeedGrader for an assignment.