In theory, this is all easy to explain.
When ingesting real life content, though, the projectionist needs a high degree of, let's call it intuition, to find and select the right content. It's nearly impossible to teach staff this in a formal way. This very often leads to either missed/incomplete content ingest, or a pragmatic 'ingest everything' approach, filling up servers quickly.
I remember specifically BigHero6, whose drive contained an overwhelming number of versions on different levels. I wonder what rules mastering studios follow to create these? Wouldn't it be useful to shed some light on complex packaging, recommendations, etc.?