View counts
To better be able to find recently visited as well as popular concepts, I have introduced two new fields in the database: viewed_count and viewed_at.
Both are updated on every view of a concept. The global list of concepts is now sorted by viewed_at and thus reflects your view history. In addition, there is a new menu entry to acces the most popular concepts, sorted by their view count.
Both fields should help to retain your flow of thinking and help you focus.