Right now you are able to review all the words in all your course at once. You are able to review all the words up for review in a single lesson. You are able to selectively review individual lessons at once.
But what I find myself wanting more and more often is the ability to select a few levels to review at the same time. I’ll go over a level, then go through a different level, and go through a third. Instead of reviewing 1, 2, and 3 individually - which is okay, but not ideal - I want the ability to select all three levels that I just learned and review them all together. It would give me the ability to mix up my review a little.