100% is not the goal

When you try to optimize a process it is very rare to reach 100% efficiency.

Short Form Rules enable you to optimize the process of adding new entries.

If 90% of the time or even more, the suggested computed short is exactly what you want and you don't have to edit it, obviously you are again sparing precious keystrokes and have hence improved your productivity.

Of course, nothing prevents you from having glossary entries that do NOT strictly follow your Short Form Rules. When adding a new entry, you can always override the computed short, if you can think of a better short than the one computed following your Short Form Rules.