ANSWER:
AIVault prepares and shows charts for Scheduled Review Dates and Length of Review Spans. Charts are opened with the "Reports" menu list, and can be of all Memos or only those in a single Memo Folder. Charts provide a visual representation of your learning process.
Plus, charts are fun. Check out how the bar colors change with how well Memos are know. Change the size and shape, watching the fonts and bars change also. Then there are mouse-pointer tooltips with bar data, and much more.