I expected after memorizing a verse, that the memory bar would degrade a lot the next day until I reviewed it. To my surprise, the memory bar stayed at 100%. This does not reflect a human's actual memory which will degrade a lot quicker without daily review, but will strengthen with continued review.
My suggestion is for the memory bar to degrade at a rate so that it would take one week to become empty right after memorizing a new verse. With each consecutive day of reviewing the verse, the memory bar would degrade proportionally less requiring fewer reviewes to keep the bar full. With enough review, a verse would take a whole year to completely degrade to 0%. These numbers are definitely up for debate, but overall I would like to see the memory degradation to reflect the reality of the human brain.