When you write a story goal script for an addon and that script does not depend on any other story goal (e.g., the script is not a subgoal), you don't need to rebuild the story. The only files required for those scripts to run in the game are the scripts themselves.

You might wonder: but how does the game know to load those scripts? I think the game must be loading all scripts at runtime. When you think about it, this makes sense: all scripts are event listeners, which run only when certain events are passed to an event manager. So, at any point in the game, there are potentially thousands of active event listeners waiting for events to occur.

Here's my workflow for independent story goal scripts:

1. Write script.
2. Generate Definitions and Build to test whether the script compiles.
3. Delete all generated files in Data\Mods\<mod> except your scripts in Data\Mods\<mod>\Story\RawFiles\Goals.

For example, mods like Auto Identify, which consists of only a single non-subgoal script, does not require the story to be rebuilt.

What are the implications of unnecessarily packaging the rebuilt story? I suppose doing so could make your mods widely incompatible, or increase the patching workload during loading screens. A developer would have to chime in about the exact consequences.