In my Master Source List, I'm in the middle of a project to make the list sort by categories.
Here's some of my concerns:
1 - Since the list cannot be sorted (on characteristics such as Author, Publisher, Publish Date, etc.) a long list becomes progressively difficult to manage and review
2 - Since RM does not allow sources to be organized into "folders" (or whatever you'd like to call the groupings), a large Master Source List can be difficult to manage
3 - Many sources have very long names, and need to be abbreviated or truncated in order to fit the available width of the available column
4 - My main database currently contains over 13,400 sources - reviewing and managing this list is awkward - finding duplicates where the display titles were abbreviated differently (I've been building my database since 1988 and in multiple programs and versions) is difficult
5 - Categorizing the sources provides a method for filtering my search - for example, all sources from published telephone records receive the prefix of [tel], causing them to sort adjacently in the Master Source List
6 - These prefixes are prepended to the display title, and do not appear in the indices of citations nor bibliography